28 to 70 nonlinear equations are required to solve for the path synthesis of planar six-bar mechanism when using the method of displacement matrix, this brings on a great deal difficuties in solving the problem and heavily limits the applied scope of the method. In this paper an incomplete parameter synthesis is presented in which the synthesis of six-bar mechanism is sim-plified to those of bar-group or four-bar machanism so that the solution becomes much easier.