Disclosed is a silicon-carbon composite material, a preparation method thereof, an electrochemical device and an electronic device. The silicon-carbon composite material includes an amorphous carbon matrix and a silicon material located on the surface and/or in the interior the amorphous carbon matrix, and has specific surface area coefficient B is 20-1250. The preparation method includes synthesizing the amorphous carbon matrix material with silicon source through chemical vapor deposition to obtain the silicon-carbon composite material. The disclosure limits the expansion of the silicon-based material to the greatest possible extent, ensures its long cycle stability and excellent conductive properties, and effectively improves the capacity and first effect of the finished material. The material preparation process is simple and suitable for industrial production.