The invention discloses a wax-based binder for metal powder injection molding. The wax-based binder comprises the following components: paraffin, E wax, polymethyl methacrylate moulding powder, an ethylene-vinyl acetate copolymer, high density polyethylene, stearic acid and an antioxidant BHT (butylated hydroxytoluene). The wax-based binder is prepared according to the following steps: putting metal powder into mixing equipment; then putting the paraffin, the E wax, the ethylene-vinyl acetate copolymer, the high density polyethylene, the stearic acid and the antioxidant BHT into the mixing equipment together, starting the mixing equipment and uniformly mixing the materials; dissolving the polymethyl methacrylate moulding powder to acetone to obtain a mixture, then putting the mixture into the mixing equipment, carrying out mixing operation till the binder is completely molten, and carrying out heat preservation for 8-12 minutes; discharging, cooling and then granulating, and feeding to finish the production of the wax-based binder. The binder disclosed by the invention is good in compatibility of components, free of phase separation, and easy to mold and remove, has the advantages of no pollution, no toxicity and the like and is especially applicable to production of Ni-Co-based products formed by metal powder injection molding.