A preparation method of silicon-based composite negative electrode material for a lithium battery includes the following steps: forming steam from a raw material A containing Si and a reducing substance raw material B capable of reacting to generate a silicate under a vacuum heating condition, condensing and depositing in a deposition system after a reaction, and then carrying out carbon coating to obtain the silicon-based composite material. A certain amount of alloy is added into the raw material B, so that a proportion of a crystal region in the silicon-based composite material can be reduced, and the initial coulombic efficiency and the cycling stability of the negative electrode material are further improved.