Abstract: The impact fatigue test of YG8 carbide under different impact energy was carried out by small energy multipunch testing machine. The lognormal distribution function was used to describe the distribution characteristics of the impact life results. SEM was used to analyze the fracture morphology after impact. The parameter estimation of probability density function was carried out with small sample, and the hypothesis testing was performed. The results show that there are two obvious fracture forms of YG8 alloy under impact load: inter-granular fracture and trans-granular cleavage fracture. The fatigue life of the group of specimens conforms to logarithmic normal distribution. The lognormal distribution is an effective method to evaluate and predict the impact fatigue data of cemented carbide.