Abstract: In order to obtain the optimal laser cutting quality and efficiency of polycrystalline cubic boron nitride(PCBN), the ablation threshold of PCBN material was obtained as 1.796J/cm², based on the function relationship between the ablation diameter and laser energy. Cutting experiments of model BN250 PCBN with Nd:YAG laser were carried out. The effects of cutting speed, laser power and pulse repetition rate on cutting quality were analyzed. The changing trend of slit width of PCBN under different laser parameters was summarized by contrasting the microscopic observation. The results show that, the best quality of slit and the higher cutting efficiency can be obtained at the condition of laser power 28W, pulse repetition rate 60Hz, and cutting speed 20mm/min, by laser pulse with pulse duration 100μs. The method and process data have an important reference value for laser processing of PCBN or other superhard materials.