A new criterion of fracture mechanics-stochastic characteristics for ceramic tool fracture based on the analysis of its fracture features in intermittent turning, is proposed in the paper. A series of experiments on mechanical performance for ceramic tool as well as cutting tests on tool life by fracture have been done. The stresses in tool tip are analysed by finite element method Allof these show that the modified distribution function of theoretical tool life by fracture derived from the mentioned new criterion presents a good agreement with the experimental results, SEM analysis on the tool fracture faces indicates the late fracture of ceramic tool appears in fatigue features