The first-principle method is employed to study the Rochow reaction. The Cu atom stably adsorbs on the Si (1 1 1) surface. The C-Cl bond of CH3Cl was broken by the Si-Cu bond only when the two bonds vertically close together. The Cu adatom triggers Rochow reaction, and seriously is an initiator. The main catalysis ability comes from Si-CH3 or Si-Cl bonds. The Rochow reaction contains two stages. The first one is that the Cu adatome triggers reaction. The second one is that the Si-CH3 and Si-Cl bonds catalyze the C-Cl bond to break and to form new Si-CH3 and Si-Cl bonds.