Abstract: Silica was modified with polymethylhydrogensiloxane by mechanochemical treatment.The modifying efficiency was characterized by TG,TR,TEM,as well as contact angle measurement.The factors influencing the modifying efficiency,such as amount of modifier,modifying time,rotating speed of the mill and ratio of ball and silica,were discussed.The results show that the surface of silica could be loaded with polymethylhydrogensiloxane by mechanochemical mothod.The loading mechanisms include both physical adsorption and chemical adsorption.When the amount of modifier is 50%,modifying time is 3 h,rotating speed of mill is 300 r·min-1 and ratio of ball to silica is 20∶1,the modifying effect reached the best and the contact angle is 150.58°.The silica modified have better dispersibility.