In order to remove the main carbon impurity methyldichlorosilane in the polysilicon raw material, it is converted into a high boiling point substance methyltrichlorosilane by a catalytic reaction. Pd/Al2O3 catalyst was prepared by impregnation method, and its physicochemical properties were characterized by X-ray fluorescence (XRF), X-ray powder diffraction (XRD), N2 adsorption desorption (BET), photoelectron spectroscopy (XPS) and H2 pulse chemisorption. Using a fixed-bed reactor under conditions where the chlorine source material is carbon tetrachloride, the catalytic effect of Pd/Al2O3 catalyst, The resin A catalyst and AlCl3/Al2O3 catalyst were compared. The effects of reaction temperature, reactant ratio, reaction space velocity and catalyst stability on the conversion of methyldichlorosilane were studied. The best process conditions were obtained. Pd/Al2O3 catalyst has better catalytic effect than The resin A catalyst and AlCl3/Al2O3 catalyst. When the chlorine source material is carbon tetrachloride, the reaction temperature is about 140 ℃、n(CH3Cl2SiH):n(CCl4)=3:1 and the space-time velocity of reaction solution is 5.0h-1, the maximum conversion rate of methyldichlorosilane can reach 69.76%.