In order to improve the corrosion resistance and electrical conductivity of TA1 bipolar plate, enhance the conversion efficiency and service life. The idea of multi-gradient composite coating was adopted, the carbon coatings with three different transition layers of Ti/CrN/a-C, Ti/TiN/a-C and Ti/TiCrN/a-C are prepared on the surface of TA1 substrate by using closed field unbalanced magnetron sputtering technology. The surface morphology, bonding hybridization form, hybrid content ratio, corrosion resistance and electrical conductivity of the carbon coating are respectively analyzed by scanning electron microscopy, raman spectroscopy, photoelectron spectroscopy, electrochemical polarization and surface contact resistance test. The result shows the carbon coatings of the three different transition layers are well bonded to the matrix, and all have amorphous carbon distribution, but the morphology and structure are different. The AD/AG value of Ti/TiN/ a-C coating is the highest, reaching 4.26, and the proportion of C-sp2 hybrid in carbon atom is the highest, reaching 79.32%. The FWHM(G) of Ti/TiCrN/ a-C coating is the highest, reaching 137.29, and the proportion of C-sp3 hybrid content in carbon atom is the highest, reaching 26.03%. Compared with TA1 matrix, the corrosion resistance of carbon coatings with three different transition layers is significantly improved.The corrosion resistance of Ti/TiCrN/ a-C coating is the best, The potentiodynamic and potentiostatic corrosion current densities are 7.81×10–7 A/cm2 and 8.14×10–7 A/cm2, respectively. It is smaller than 2.76×10–6 A/cm2 and 3.21×10–6 A/cm2 of TA1 matrix, respectively. In addition, the surface contact resistances of carbon coatings with three different transition layers are 12.3 m?.cm2, 5.4 m?.cm2 and 6.5 m?.cm2 under 1.4 MPa compression force, respectively. which is less than 93.5 m?.cm2 of TA1 matrix, it‘s about an order of magnitude lower through calculation. In conclusion, By doping different elements and controlling the target flow of process parameters, different nitride transition layers with varying composition gradient are deposited. which influences the deposition effect of pure carbon in the outermost working layer, and its morphology and structure are changed, thus its conductivity and corrosion resistance are improved.