Mo-Cu (Mo:Cu=60:40, mass ratio) predecessor powder was prepared by chemical co-precipitation taking (NH4)6Mo7O24·2H2O and CuSO4·5H2O as starting materials. And then the Mo-Cu predecessor powder was reduced by hydrogen in closed circulation system to prepare the Mo-Cu composite nano-powder. The results reveal that conditions of the chemical co-precipitation are that reaction temperature is (50±5) °C, pH value (5.1±0.1), and ageing time (9±1) h. Under the conditions mentioned above, the average particle size of the prepared the Mo-Cu predecessor powder is 20 nm. The hydrogen reduction temperature during closed circulation is 650 °C. The particle size of obtained Mo-Cu composite powder is less than 100 nm.