Ni-Cu-P alloy was produced by electroless deposition, and the different microstructures were obtained by low-temperature heat treatment. Effect of element Cu on microstructure evolution and corrosion resistance of Ni-Cu-P alloy was studied by X-ray diffraction (XRD), transmission electron microscope (TEM) and electrochemical examination. The results showed that the crystalline behavior of Ni-Cu-P amorphous alloy was a gradual process during the heat treatment process. However, the corrosion resistance of Ni-Cu-P alloy was firstly enhanced and then deteriorated during the heating process. The corrosion resistance of the alloys was not only affected by the crystalline precipitates, but also influenced by the alloying elements in the coatings. In comparison with the Ni-P samples under the same states, the incorporated copper enhanced the thermal stability and corrosion resistance of the Ni-Cu-P samples. The Mott Schottky (M-S) results showed that the passive layer on ternary Ni-Cu-P had p-n bipolar semiconductor characteristic, however the binary Ni-P passivation film showed only one p type semiconductor characteristic in 3.5 wt% NaCl solution.