CrN/ta-C composite coating on a high-speed steel substrate is performed by magnetic filtered cathodic arc technique and magnetron sputtering technique. Adheision of ta-C film on the high-speed steel substrate is studied by changing the preparation process of a buffer layer of CrN. The results are as follows. With the increase of nitrogen flow, the buffer layer chromium nitride experiences the phase transition of Cr-Cr2N-CrN; the adhesion of the coating is improved with the increase of nitrogen flow, but when the nitrogen flow exceeds 30 sccm, the adhesion of coating will decline; the preferred orientation and grain structure of chromium nitride are changed by adjusting the substrate bias; the adhesion of the coating is improved with the increases of the bias voltage, but when the bias voltage exceeds 200 V, the the coating adhesion characteristics will be slightly reduced. The abrasion resistance of the test also shows that CrN coating can significantly improve the adhesion of the ta-C film on a substrate of high speed steel, and can also significantly improve the wear characteristics.