Abstract: There is a large amount of silicon in the filter residue after extracting titanium from the titanium slag roasted with ammonium sulfate. Kinetics of alkaline leaching process of extracting silicon from the residue of titanium extraction were investigated. The results show that the internal diffusion on the solid product layer is the rate-controlling step in the leaching process. According to the Arrhenius expression, the apparent activation energy for the alkaline leaching process is 28.91 kJ/mol. The kinetics equation can be expressed as 1+2(1-x)-3(1-x)^2/3=4.8554exp-28910/(RT)•t.