| Wood characteristics of acacia mangium willd, acacia crassicarpa, acacia auriculiformis willd,and acacia aulacocarpa such as fiber morphology, chemical composition and basic density etc, which have significant impact on properties of pulp made by chemical pulping process, were determined and analyzed in this study. The pulping properties of these four acacia wood species were evaluated by kraft pulping process, and the suitable pulping conditions were determined, and the bleachability of these four acacia kraft pulps made from suitable pulping conditions were evaluated by chlorine-containing bleaching process and ECF bleaching process respectively. The results showed as follows:The wood characteristics analysis showed that extractives and lignin contents of A.crassicarpa and A.aulacocarpa were closed and more than those of A.mangium willd and A.auriculiformis willd, and their holocellulose contents of A.mangium willd and A.auriculiformis willd were closed and more than that of the formers; All the four acacia wood species have a closed fiber morphologies and which average fiber length are about 0.90 mm to 0.96 mm, the basic density of A.crassicarpa is about 0.58 g/cm3 higher than that of others, A.aulacocarpa is about 0.55 g/cm3 followed that of A.crassicarpa, and A.mangium willd and A.auriculiformis willd have a closed basic density about 0.48 g/cm3 and 0.47 g/cm3 lower than that of other two acacia woods..The study of kraft pulping properties of four acacia wood species showed that at the same active alkali dosages of 16% (as for Na2O), the kappa number of A.mangium willd pulps could reach about 17.7 lower than that of others, A.mangium willd and A.auriculiformis willd have a closed kappa number little higher than that of the former, and A.crassicarpa pulp's has the higherst kappa number compare with the other pulps', it is about 20.38. At this cooking conditions, the Y/K (screened pulping yields to kappa number ratio) number of both A.mangium willd and A.auriculiformis willd are closed abot 2.80, and it is about 2.59 for A.aulacocarpa pulping little lower than the formers, and A.crassicarpa pulping has the lowest Y/K number of 2.39 compare with other acacia woods.The study of beating properties of these pulps showed that at the revolution about 9000 Rev, the tensile strength properties of A.auriculiformis willd pulps could reach about 84.27N.m/g, and it could reach about 83.65N.m/g and 83.76N.m/g respectively for both A.mangium willd and A.auriculiformis willd pulps, and the tensile strength properties of A.crassicarpa pulp is the lowest about 76.27N.m/g than that of other acacia pulps..All four acacia kraft pulps bleached with CEH bleaching process at the same total active chlorine dosages of 4.62% showed that the A.auriculiformis willd kraft pulp has the best bleachability among these four acacia pulps, and it could be bleached up to 77.9 %ISO; and it could be bleached to 77.5 %ISO for A.mangium willd pulp and it followed the formers; and it could only bleached to 73.9%ISO and 72.8%ISO respectively for both A.crassicarpa pulp and A.aulacocarpa kraft pulp, they are lower than thant of the other acacia pulps; The study of beating properties for a closed brightness of these pulps about 77%ISO showed that at the same beating degree about 45 oSR, the tensile index and the burst index of A.auriculiformis willd bleached pulp are the best than that of other pulps and it could reach about 79.95N.m/g and 5.78kPa.m2/g respectively, and the tensile index and the burst index of A.crassicarpa bleached pulp is the lowest compare with other pulps, they could only reach about 66.39N.m/g and 4.73kPa.m2/g respectively.The study of CEHD bleaching properties for these pulps showed that at the same total active chlorine dosages of 5.12 %, the brightness of A.auriculiformis willd bleached pulp could reach about 84.7 %ISO; A.mangium willd pulp and A.aulacocarpa pulp have a closed bleachability and both pulps could be bleached about 83.6 %ISO and 83.4%ISO, and the A.crassicarpa pulp has the worst bleachability comparewith other pulps and it could only be bleached to 81.5%ISO. The study of beating properties of these pulps showed that at the same beating degree about 45 oSR, A.auriculiformis willd bleached pulp has the beat tensile index about 79.14N.m/g compare with other pulps, and the tensile index of both A.mangium willd pulp and A.aulacocarpa pulp could reach about 75.43 N.m/g and 73.25 N.m/g respectively;A.crassicarpa bleached pulp has the lowest tensile index about 69.27N.m/g compare the others.The study of ECF bleaching properties of these acacia pulps showed that at the hydrogen peroxide reinforced oxygen delignification (OEP) stage, the residual lignin of A.auriculiformis willd kraft pulp could be removed easiest than that of others, and the delignification could reach about 50.3%; and the residual lignin of A.aulacocarpa pulp is the most difficult to removed compare with others, and it could just only reach about 46.8%. The study of OEPDP bleaching for these pulpsshowed that at the same conditions of 1.5% chlorine dioxide dosages and 1.5% hydrogen peroxide dosages, all these four acacia pulps could be bleached up to 85%ISO. it has a closed bleachability for both A.mangium willd pulp and A.auriculiformis willd pulp and both pulps could be bleached to 87.8%ISO and 87.1% ISO respectively, and it has a closed bleachability for both A.aulacocarpa pulp and A.crassicarpa pulp and they could be bleached to 85.9% ISO and 85.6% ISO respectivelylower than that of the formers,The study of beating properties of these pulps showed that at the same beating degree about 45 oSR, A.auriculiformis willd bleached pulp has the beat tensile index about 80.85N·m/g compare with other pulps, The tensile index of both of A.mangium willd and A.aulacocarpa bleached pulps could reach 79.10 N·m/g and 77.14N·m/g respectively;A.crassicarpa bleached pulp has the lowest tensile index about 72.48 N·m/g compare the others pulps.The comprehensive kraft pulping potential of these acacia wood species could be summarized that the acacia uriculiformis Willd is the best one among four wood species of acacia wood, acacia mangium Willd and acacia aulacocarpa are medium, and acacia crassicarpa is the worst one.
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