The invention discloses a Si/SiC composite material for a lithium ion battery, a preparation method of the Si/SiC composite material, a negative electrode made of the material and the battery. The composite material is prepared by compounding a Si nano material and a SiC nano material, wherein the existing form of the SiC nano material at least contains a SiC nanowire. The preparation method of the Si/SiC composite material comprises the following steps: compounding a silicon oxide/carbon composite porous block material and a conductive cathode current collector to form a cathode; setting an anode and putting the cathode and the anode into electrolyte containing metal compound fused salt; applying voltage between the cathode and the anode; controlling electrolysis time under inert atmosphere and preparing the Si/SiC composite material on the cathode. According to the Si/SiC composite material provided by the invention, the SiC nanowire and the Si nano material are generated at the same time and are in sufficient contact; the SiC nanowire has relatively high mechanical strength and damages, caused by inner stress generated by volume expansion of the Si negative electrode in a lithium insertion/extraction process, to an electrode structure can be alleviated; the mechanical properties of the Si negative electrode are improved, so that the circulating performance of the Si electrode is improved.