Abstract: Ti-B-C-N films with nitrogen atom fractions of 10.8%, 15.6%, 28.1%, 36.4% were prepared on high speed steel matrix by reactive magnetron sputtering. The effects of nitrogen content on microstructure, hardness and friction and wear properties of the films were studied. The results show that the Ti-B-C-N films were all composed of α-Fe and Ti(C, N) nanocrystals, and had a nano-composite structure composed of Ti(C, N) nanocrystals embedding in amorphous matrix phase. With the increase of nitrogen content, the content of amorphous phases increased, and the content and grain size of Ti (C, N) nanocrystals decreased. With the increase of nitrogen content, the microhardness of the Ti-B-C-N films increased, and the friction coefficient and the wear rate decreased; the surface wear marks became shallow, and the wear mechanism changed from spalling and micro-ploughing to micro-polishing.