Special consideration must be applied in the analysis of fatigue life of composite materials due to its high scattering in mechanical property. The relationship between fatigue life Weibull shape parameter and residual strength shape parameter of M21C open-hole composite laminates were deduced based on the Sendeckyj equivalent static strength model and probability distribution of functions of random variables. The fatigue life shape parameter and fatigue threshold of M21C open-hole composite laminates were obtained through element tests and statistic analysis, which can provide support for the determination of LEF (load enhancement factor) and truncation levels for low loads of M21C composite material system.