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To solve the problems that ceramic tools were sensitive to cracks, ZrSi2 crack repairing agent was added into Si3N4/TiC ceramic tool material matrix, which made ceramic tools have crack repairing ability. When ZrSi2 content was as 10% (volumn fraction), Si3N4TiC/ZrSi2 ceramic tool materials had better comprehensive properties, with flexural strength of 815 MPa, fracture toughness of 8.06 MPa ⋅ m1/2, Vickers hardness of 15.91 GPa and relative density of 99.72%). Cracks were introduced into the surface of ceramic tool materials by Vickers hardness tester, and the optimal repair parameters and repair mechanism of cracks in Si3N,/TiC-based ceramic materials with ZrSi2 as repair agent, were studied. The research shows that the flexural strength of Si3N4TiC/ZrSi2 prefabricated crack specimen with 10%) ZrSi2 added may be restored to 92.02%) of that of smooth specimen after heat treatment at 800 °C for 60 min in air atmosphere, and the crack with the surface length of 300 ~ 350 µm is completely repaired, and an oxide layer mainly composed of ZrO2 and SiO2 is formed on the surface of the specimen. The mechanism of crack repair of ceramic cutting tool materials is analyzed as follows-, in the air heat treatment processes, ZrSi2, a healing agent at the crack and the surface of the material, preferentially reacts with oxygen to generate ZrO2 and SiO2, which heal the crack on the surface of the material and restore the strength of the crack sample. At the same time, during cutting, ZrO2 and SiO2, oxidation products of ZrSi2 at the cracks and material surfaces, may repair the crack in time and improve the wear resistance of the tool. [ABSTRACT FROM AUTHOR]