Objective To analyze the diversity of the composition and structure of the two kinds diamond-like carbon ( DLC) film and study its application of anti-friction in the engine. Methods The composition and surface morphology of the film were analyzed, the effect of DLC film on the surface of piston pin on the components organization material and hardness was discussed, the influence of the application of the DLC film on piston pin on engine mechanical loss power was verified, tribological mechanism of membrane and graphitization were analyzed and discussed. Results Benchmark coating was W-doped DLC films and was thicker. Benchmark coating specimens were better than the research coating technology in the phase density, uniformity and the bonding state. After the application of finished piston pin on DLC coating, it showed that the power performance of engine had been improved when the speed between the ranges of 2200 ~ 4000 r / min. Conclusion Application of DLC film can effectively improve the surface state of piston pin and reduce parts wear under the working conditions, and thus extends the service life of piston pin.