The invention discloses a preparation method of a lithium ion battery copper nitrate composite negative electrode material. The preparation method is characterized by including the following steps of taking 300-500 g of copper nitrate powder and 5-10 g of lithium nitrate, dispersing the copper nitrate powder and the lithium nitrate in 300 ml of mixed solution of N-methylimidazole and absolute ethyl alcohol, raising the temperature to 60 DEG C after the copper nitrate powder and the lithium nitrate are completely dissolved, adding 100 ml of 2-chlo-1,3-dimethyliazolidinium tetrafluobate, raising the temperature to 80 DEG C, stirring the mixture for 10 minutes at a high speed, adding 5-10 g of carbon nano-tubes, continuing to stir the mixture for 180 minutes at a high speed, conducting decompress filtering, putting the product obtained through filtering in an oven to be baked for 72 hours at the temperature of 60 DEG C, taking out the product, and grinding the product into powder to obtain the copper nitrate composite negative electrode material. The method has the advantages that the obtained copper nitrate composite negative electrode material has a stable composite structure and has high capacity and long service life due to the composite structure.