Objective To improve the fretting wear fatigue resistant life of the helicopter rotor system connector and solve the environmental pollution problem caused by the traditional chrome plating craft. Methods By optimizing the oxygen-fuel ratio of oxygen and acetylene mixture, WC-12Co coating with high hardness and dense structure was deposited on the 35Ni4Cr2MoA high-strength steel substrate using the detonation spraying method. Influence of oxygen-fuel ratio on the composition, structure and mechanical property of the coatings was researched. Results The results showed that the carbon content of the coating decreased with increasing oxygen-fuel ratio. With the increase of the oxygen-fuel ratio, the hardness, density, elasticity modulus and bonding strength of the coating first increased and then decreased. When the oxygen-fuel ratio was less than 1. 1, the coating hardness and density decreased mainly due to the lower flight speed and insufficient melting of particles. When the oxygen-fuel ratio was more than 1. 3, oxidation and decomposition of WC particles in the oxidizing atmosphere of the explosion flame flow exacerbated the loss of carbon element. When the oxygen-fuel ratio was 1. 2, the coating showed no significant oxidation and decar-burization. The section Vickers hardness HV0. 3 reached 12. 9 GPa and the porosity was 0. 86% . The bonding strength between the coating and the substrate reached 148 MPa. Conclusion The high-speed particles in the process of explosion spraying had a surface strengthening effect on the 35Ni4Cr2MoA high-strength alloy steel substrate. After deposited WC-12Co coating using detonation spraying, the fatigue life of shot-peened test rod could be enhanced by 107. 4% . The oxygen-fuel ratio had a significant effect on the composition, structure and mechanical property of the WC-12Co coating deposited using the detonation spraying method. When the oxygen-fuel ratio was 1. 2, the coating showed no significant oxidation and decarburization and had an optimal comprehensive mechanical property.