The work aims to improve corrosion resistance of metal materials in high temperature, high pressure and high chloride corrosion environment. Ni-W-P alloy coating and Ni-W-P-nSiO2 composite coatings were prepared on L245 steel by chemical plating. Structure, morphology, hardness and porosity of the coatings were characterized with X ray diffractometer (XRD), scanning electron microscope (SEM), microhardness tester and in filter paper method. 72 h uniform corrosion tests were carried out by simulating field conditions in a high temperature autoclave at 150 ℃, 35 MPa, and corrosion rate was calculated in weight loss method. The Ni-W-P coating and Ni-W-P-nSiO2 composite coatings were all amorphous structures. SEM observation showed that the surface of the three coatings were cellular, and the nano silica adsorbed on the surface of the substrate make the microstructure of Ni-W-P-nSiO2 composite coating smaller as a nucleation core. Porosity of the composite coatings containing nSiO2 decreased from 1.24 to 0.83. Hardness of magnetic stirring and ultrasound-assisted Ni-W-P-nSiO2 composite coatings was 491.6HV and 421.7HV, respectively, which was 107.1HV and 37.2HV higher than that of Ni-W-P coating (384.5HV), respectively. The corrosion rates of magnetic stirring and ultrasonic assisted Ni-W-P-nSiO2 composite coatings were 0.0552 mm/a and 0.0371 mm/a respectively, 1/2 and 1/3 of 0.1075 mm/a of Ni-W-P coating. Surface composition analysis after corrosion indicated that the surface corrosion product of ultrasonic-assisted Ni-W-P-nSiO2 composite coatings was Ni3S2 film, which could effectively protect the substrate. Compared with Ni-W-P alloy coating, the corrosion resistance of ultrasound-assisted Ni-W-P-nSiO2 composite coatings is obviously improved.