Abstract: A simplified method is used for evaluating the reliablity for the existing strucural system,which is based on the analytical hierarchy process and the first-order second-moment method.Combination of the reliability of members by different weighing parameters(ratio of load vs.resistance with some modifications) is defined as the storey reliability.The minimum value of the storey reliability is defined as the reliability of the whole structural system.The shear failure model of wall is the main fault model of wall member under earthquake,so the benefit function is defined as the shear resistant capacity of the wall minus the corresponding earthquake reaction.The formula of the shear resistant capacity of wall in the current design code can be used here.Engineer case is presented here to demonstrate this method for aseismic reliability of the existing masonry structures.