The invention relates to a method for producing trichlorosilane by coldly hydrogenating silicon tetrachloride. The method comprises the following steps: mixing and vaporizing the silicon tetrachloride and hydrogen before entering a high-pressure state together with silicon powder and catalyst copper powder and entering a barrel-shaped cold hydrogenation reactor; continuously reacting in the barrel-shaped cold hydrogenation reactor under the conditions that temperature is 300-500 DEG C, pressure is 1.5-5.5 MPa, pH value is 5-7, and mixing gas velocity is 12 m/s to generate the trichlorosilane. The method can produce trichlorosilane directly for producing polysilicon at an electronic grade, improves the conversion efficiency (achieves 30-35 percent), circularly utilizes materials in the whole process, has no pollution, is beneficial to environmental protection, reduces enterprise cost and increases enterprise benefits.