The phase transformation of xPMnS-(1-x)PZN quaternary piezoelectric ceramics was studied and the effect of composition on phase transformation characteristics was also discussed. Results indicate that xPMnS-(1-x) PZN ceramics show disperse phase change characteristic and obvious dielectric thermal lag in the course of the phase change. The result of electronic structure investigation indicates that the disperse phase change should be attributed to the difference in strength of B—O bonds. The material has relaxation ferroelectric characteristics When x value is large (or small), and shows relatively strong disperse phase change. It has normal-relaxation ferroelectric characteristics when x value is near 0.4, and shows relatively weak disperse phase change.