Abstract: Removing of trichlorosilane，which is often found in silicon tetrachloride with photochemistry method was studied using raw silicon tetrachloride from market as material.Major factors influencing photoreaction effect and relationship of these factors were analyzed during the photoreaction process using ultraviolet light at 330~380 nm.Results showed that photoreaction time increases with the dosage of raw material increases and the decrease of light intensity.In order to remove trichlorosilane,the amount-of-substance ratio of chlorine to trichlorosilane must be greater than 22∶1 at least.There existed a critical value,when amount-of-substance ratio of chlorine to trichlorosilane was not over it，photoreaction time decreased as the amount-of-substance ratio increased，otherwise photoreaction time will only increased.In addition,the bigger the light intensity,the smaller the critical value. 

Key words: silicon tetrachloride, trichlorosilane, photochemical reaction