Objective To study the performance of Zn/Ni composite coatings on 300M high-strength steel surface, which were deposited by cold gas dynamic spray. Methods The coating was sprayed by Zn and Ni physical mixture powder on 300M high-strength steel surface. The morphology and microstructure of the coatings were analyzed by the SEM images, EDS and microhardness tester. The corrosion resistance of Zn/Ni coatings was comprehensively investigated by neutral salt-spray test, coating furcated test and atmospheric exposure test. The effect of cold spray on the fatigue property of 300M steel substrate was tested. Results The surface and cross-section SEM images indicated that the cold sprayed Zn/Ni composite coatings were very compact, without pores and cracks, the porosity of Zn/Ni coatings was 0.4% and the bonding strength was 40 MPa. The EDS analysis result showed that the mass fractions of Zn and Ni in the Zn/Ni composite coatings were about 85% and 15%, respectively. The microhardness of Zn/Ni coatings was 70.8HV0.49, this is because the hardness of the coatings was improved by the strengthening effect of Ni in the Zn/Ni coatings. Cold sprayed Zn/Ni composite coatings had very good corrosion resistance. The salt spray result of Zn/Ni coatings could reach 770 h, and it could reach 600 h even at coatings failure. No obvious corrosion was observed on the surface after 12-month atmospheric exposure test, and cold spray had no influence on the fatigue property of 300M steel substrate. Conclusion Cold sprayed Zn/Ni composite coatings could be used as efficient corrosion-resistant coatings on 300M high strength steel surfaces.