Synthesis method of polycarbosilane capable of being used for thermosetting crosslinking

A synthesis method of polycarbosilane capable of being used for thermosetting crosslinking comprises the following steps: taking polycarbosilane used for preparing a composite material as a raw material; placing the polycarbosilane used for preparing the composite material and an organosilan compound containing 2 to 3 -C=C- groups into a reaction vessel; adding dimethyl benzene; mixing uniformly for dissolving; adding a Si-H additive reaction catalyst; vacuumizing; carrying out replacing with high-purity nitrogen; carrying out an Si-H additive reaction under a normal-pressure or high-pressure heating condition and the protection of the high-purity nitrogen. The synthesis method is simple and convenient, and easy to implement; the product PVCS can be used for self-setting crosslinking under an inert atmosphere after being treated at 400 DEG C; the smelting outflow of PCS during heat treatment can be avoided; the ceramic yield can be improved remarkably; the polycarbosilane synthesized according to the synthesize method can be used as a precursor polymer of ceramic-based composite materials such as Cf/SiC, and SiCf/SiC.