The open circuit potential of electroless copper plating on process was measured by electrochemical workstation, and the copper-coated tungsten composite powder and tungsten strip after plating were characterized. The results show that during electroless copper plating, the initial open circuit potential is about -600 mV, and changes through slight increase and rapid drop, and becomes stable at about -870 mV in a short time, then follows a sharp rise, and finally reaches -690 mV in 300 s, in the meantime it remains stable and the copper thin-film plating is accomplished. The composite complexing agent of EDTA×2Na and TART can facilitate the copper plating reaction through adjusting the charge distribution on the surface of tungsten particles. Trace (≤10 mg/L) of 2,2￠-pyridine can effectively restrain the formation of Cu2O and improve the quality of the film.