PVD or CVD Me-Si-N nanocomposite films synthesized by doping Si element in metallic nitride matrix have exhibited good oxidation resistance and wear resistance. As melting the alloy target containing Si is not easy, it is difficulty to dope much more Si in the films by PVD techniques. In addition, the Me-Si-N films do not have enough lubrication. In this paper, Cr-Si-C-N films were prepared by cathode arc ion deposition technique, in which tetramethylsilane (TMS) was used as Si and C sources, and their concentrations in the Cr-Si-C-N films can be controlled by TMS flow. The state of chemical bonding, microstructure and microhardness were investigated by XPS, XRD, HRTEM and microindentation hardness tester. Results show that the Si and C contents increase monotonicly with the increase of TMS flow. When the TMS flow is lower than\linebreak 90 mL/min, the Cr-Si-C-N film has a composite structure of Cr(C, N) nanocrystals dispersing in the amorphous Si₃N₄ (nc-Cr(C, N)/a-Si₃N₄), and the microhardness increases to 4500 HK with increasing TMS flow. Such high hardness originates from the solid solution hardening of the doping fewer element and the Veprek nanocomposite structure hardening mechanism. With the further increase of TMS flow, the hardness decreases because of the appearance of free C.