Abstract: Stochastic damage tolerance method based on the stochastic fracture mechanics is one of the most important aspects of design and evaluation technique of aircraft structure. Stochastic damage tolerance analysis model is constituted with random crack propagation model and reliability analysis model. The random model of crack propagation corresponding to interactive multi-crack has been presented in this paper. Some basic concepts are discussed, for instance: far cracks, near cracks, stochastic-life camber. A unified differential equation of multi-crack propagation is established. Basing on some engineering hypothesis, the calculation of crack propagation has been abbreviated. The damage tolerance technique has been developed in the paper. A large progress has been made on stochastic damage tolerance analysis of multi-cracked structure.