Abstract: Based on analyzing the structure of industrial crystallizer impellers, their parametric design was realized with pitch ratioh/D, blade area ratioAE/AOand draft tube-stir tank diameter ratiod/D′as the basic parameters. Based on the principle that all points in a crystallizer have the same flow rate, a general purpose CFD (computational fluid dynamics) software Fluent was used in the quantitative analysis of the flow field in a crystallizer, and the optimization parameters was obtained,i.e. h/D=1.2, AE/AO=0.7 andd/D′=0.63.