Abstract: To improve the holding force between the diamond and metal matrix bonding, the Ni-coated diamond was treated at 1050 for 1 h, th℃ en the diamond surface was cleaned by the concentrated nitric acid, finally, the Cu-matrix bonding diamond segments were prepared by vacuum hot-pressing sintering. The surface morphologies of diamond coatings before and after high temperature treatment were observed by scanning electron microscope. The flexural strength of Cu-matrix bonding diamond segments was measured to evaluate the holding force between diamond and Cu-matrix bonding. The phases between the coating and diamond after high temperature treatment were analyzed by X-ray diffraction. The results show that, the Ni coating treated at 1050 for 1 h mainly℃ maintains integral and the diamond surface was roughened. The flexural strength of Cu-matrix bonding diamond segments increases from 759 MPa for the uncoated diamond to 791 MPa for the Ni-coated diamond, and then to 833 MPa for the Ni-coated diamond after high temperature treatment, showing the effective improvement of the holding force between Ni-coated diamond and Cu-matrix bonding.