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">Optimum process conditions of potassium sulfate crystallization in bentonite interlayer were studied from four factors,namely stirring time,stirring speed,pulp liquid/solid mass ratio,and supersaturation degree of potassium sulfate.Optimum reaction conditions and primary-secondary reaction conditions were obtained by orthogonal experiment.Slow-release effect of the product was researched simultaneously.Optimum process conditions were as follows:pulp liquid/solid mass ratio was 5,stirring speed was 2 m/s,stirring time was 30 min,and degree of supersaturation was 0.15.From the photoes of SEM,potassium sulfate remained in bentonite has entered into the interlayer.</SPAN>