The work aims to improve the corrosion resistance of aluminum alloys based on good electrical conductivity. A layer of Ni-P alloy was electroless plated on the surface of aluminum. The effects of coating thickness on the corrosion resistance and electrical conductivity of the samples were investigated. Corrosion resistance of aluminum alloys with and without Ni-P coatings in simulated tunnel seepage environment was analyzed by electrochemical test and immersion test. When the thickness of the electroless Ni-P coating was 11.6 μm, the coating was dense without pinholes and the surface was smooth, with uniform distribution of the cauliflower-like nodules and the sample had the best electrical and corrosion resistance. The resistivity of the sample increased as the coating thickness increased. When the thickness of the coating was 11.6 μm, the measured volume resistivity of the sample was 3.01×10–8 Ω?m. The impedance value of the sample in 3.5wt% NaCl solution increased first and then decreased with the increase of the thickness of the coating. The sample had the best corrosion resistance when the coating thickness was 11.6 μm. In the corrosion medium of pH=2, 3.5wt% NaCl and pH=12, the self-corrosion current density of the samples after electroless nickel plating was reduced by 30%, 60% and 5 orders of magnitude, respectively, relative to the aluminum matrix. The Ni-P coating with a thickness of 11.6 μm can give the aluminum alloy the best corrosion resistance in each simulated environment while ensuring good electrical conductivity.