Composite stiffened plates under axial compression of a tortuous process,have many failure modes, and there are different impact on its entire reliability. By using Abaqus software to establish stiffened composite plates progressive failure model, the shell-solid elements to simulate the stiffened plates and beams, solid elements to simulate the layer ,and cohesive unit to simulate the situation debonding layer.Through finite element simulation method using application of MFOSM to calculate reliability analysis under tortuous process, main factors influencing the reliability is static force. Through the sensitivity analysis, the normalized calculation, the rate of contribution was gotlen, with different elastic moduli of composite material model, that of substrate failure,fiber failure,interface layer failure and static of failure rate of contribution. The failure judgment index showed that fiber failure are the main factors causing failure of stiffened composite plates structure. The sensitivity analysis results show that the substrate failure, fibers failure, interface Layer failure, are the main factors.