To reduce the matrix hardness of diamond composites for hard rock formations, Cu-based composites with lower sintering temperature and hardness were prepared by medium-frequency induction hot press sintering in this paper, with the addition of basalt fiber particles (BFPs) of 0 wt%, 1 wt%, 3 wt%, and 5 wt%. The microstructural characterization and property tests were carried out to research the effects of BFPs on the flexural strength, hardness, densification, and wear ratio of the composite. The result shows that when the BFPs addition was 1 wt %, the holding strength of the composites was increased by 10.3 % the hardness was increased by 5.9 % compared with the blank sample, and the diamond exposure became higher in the wear ratio test. The BFPs enhance the homogeneity of the composite structure, promote the diamond exposure in the composites, improve the holding strength of the composite of the diamond, and reduce the thermal damage of diamonds in the composites.