Abstract: <SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: "Times New Roman"; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体">Key points in the design for the process of freezing crystallization were discussed by analyzing influencing factors.In addition,influence of supersaturation on primary nucleation in crystallization process was analyzed and method that through controlling circulation rate of mother liquid to control the supersaturation so as to avoid primary nucleation was studied.Internal structure of chiller-crystallizer was improved so that crystal nucleus could become the suspension state and mix with supersaturation solution completely in crystallizer and finally achieve the purpose of promoting growth of crystal.New equipment design also fully considered how to reduce the probability of crystal secondary nucleation.Meanwhile,fine crystal discharge device was added in crystallizer to decline quantity of crystal nucleus and to increase crystal growth rate so as to reach the aim of improving crystalline quality.</SPAN>