The statistical characteristics of load and resistance of gravity quay against sliding and overturning with wave force are investigated.And simplified expressions in which the parameters are determined based on the reliability outcome of 10 block quays and 46 caisson quays using JC method are proposed.It indicates that the wave force has a strong influence on reliability of the gravity quay.In the case of same type of gravity quay and same back filler,the bias and variation coefficients of the load and resistance for sliding and overturning can be regarded as constants.The results of reliability index obtained by simplified expressions are very close to the results obtained by JC method.