| Content: After QCD (quantum chromodynamics) became a fundamental theory of strong interactions, one predicted the existence of a new kind of hadronic states, which contain no quarks as their constituents; instead, their constituents are massless gluons. Gluons can form bound states called glueballs through self-interactions of gluons. Glueballs are a peculiar prediction of QCD as a kind of non-Abelian quantum field theory, whether they can be identified in experiments is decisive in testing QCD in low-energy region. Therefore study of glueballs not only helps elucidating QCD theory, but also plays an important role in the development of low-energy hadronic physics.Exploring glueballs almost began as soon as QCD was established. With the deep insight in experiments and theory, new candidates for glueballs are found. But up to date, glueballs can not be identified unambiguously. The reason for this is twofold: on the one hand, glueballs, especially scalar ones, lie in the energy region in which common mesons abound, they can mix with each other; on the other hand, one can not handle nonperturbertive problems efficiently, instead, various models must be assumed, which decreases the reliability of predictions considerably. The predictions given by different models are controversial usually. In spite of this, now one shares the common views: the masses of glueballs given by various models are consistent on the whole; mixing between glueballs and mesons must be taken into accounted.Three main candidates for scalar glueballs are f 0(1370), f 0(1500) and f0 (1710). In this paper, we explore their structures and decays phenomenologically by using the newest experimental data. We assume they are mixing states of quark-antiquark and two-glue states, then calculate their branch decay ratios , explore their structure by fitting. In our calculation, different mixing modes are taken into account and we analyze the effects of different parameter values.
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