The invention relates to a preparation method of nanometer WC-Co composite 
powder, which belongs to the technical field of preparation of a nanometer 
composite material. The preparation method is characterized in that nanometer WC 
powder of which the grain size is 30-200 nm is used as a 
raw material, the 
raw material of the nanometer WC 
powder can be subjected to low-temperature ultrasonic 
chemical plating by adding plating solution in the nanometer WC powder after the nanometer WC powder is sensitized, cleaned, activated, cleaned and dispersed by adding a dispersing agent under an 
ultrasound condition, the plating liquid for 
chemical plating is formed by 14-26 g / l of CoSO4.H2O, 100-150 g / l of KNaC4H4O6.4H2O, 18-40 g / l of NaH2PO2.H2O and 40-60 g / l of (NH4)2SO4, and pH (Potential Of 
Hydrogen) of the plating liquid is controlled to be 8-11 while plating is carried out. According to the preparation method disclosed by the invention, the problem that nanometer WC is easy to unite during a 
chemical plating process is solved, a uniform metallic 
cobalt clad layer is obtained on the surface of the nanometer WC, the technological process is simple, the cost is lower, the size of the prepared nanometer 
composite material is less than or equal to 260 nm, and the defect of the prepared nanometer 
composite material in application can be greatly improved.