The optimum thickness of Pd-Ni plated layers used as an electrical contact film was investigated by evaluating mechanical, thermal and environmental characteristics. The variations of morphologies and chemical compositions were studied by using SEM, EDS and ESCA. As a result of wear test, the wear resistance behavior of the gold plated layers was not changed with the sliding velocity changes. The palladium-nickel plated layer showed better wear resistance than the gold plated layer at low sliding velocity, but it showed poor wear resistance at high sliding velocity. Under the thermal condition of $400^{circ}C$ in air, the gold thickness of $2mu extrm{m}$ without underplate on phosphorous bronze formed copper oxide on the surface layer by rapid diffusion of copper whereas the gold thickness of $0.8mu extrm{m}$ deposited on nickel and palladium-nickel underplate was stable at $400^{circ}C$. Under the sulfur dioxide environments, the gold thickness of $0.3mu extrm{m}$ deposited on the nickel thickness of$ 3mu extrm{m}$ and the palladium-nickel thickness of $2mu extrm{m}$ underplate was more corrosion-resistant than the gold thickness of $2mu extrm{m}$ without underplate on phosphorous bronze. Under the nitric acid vapor environment, corrosion resistance of the gold film was superior to an equivalent thickness of the palladium-nickel film.