| The design of plane four-bar mechanism is very important on the engineering practice. It has been focused by mechanists all the tune. With the development of computer technology, the demand of precise product get more tough, and then, many fuzzy matters occur. Accordingly, to deal with these fuzzy problem will be correspondent with fuzzy method. Although many new methods of four bar mechanism with trace occurred, the problem of how to extract character of locus curve and how to destine them is still the main topic of four bar mechanism trace design.The paper introduce a new method extracting character of locus. The author connectted numeric with geometrical method. And then every locus curve has a grupe of parameters. When all parameters are input to computer, we can get a electronic graph book. The paper use fuzzy theory to tell curves, the preciseness has been improved. Forethermore, this method enable results match engineering fact much more. During the course of optimism, the paper also use the fuzzy theory to deal with fuzzy matters in design. At last, the result satisfied designer mostly. |