A membranous disc coupling design method was proposed based on the standpoint of fatigue life analysis, to select and evaluate the molding surface function at a given operating condition. The method of modeling membranous disc in finite element method(FEM) was discussed, and the boundary conditions were derived based on this FEM model. A dynamic analysis method was presented to get the stress caused by complex operating condition. Based on dynamic stress analysis, effects on fatigue life caused by several typical complex operating conditions were given. Fatigue life of three typical membranous disc couplings with different molding surface were compared, and the method of evaluate the design of molding surface of membranous disc coupling by fatigue life analysis was suggested. The corresponding operating conditions of the typical molding surfaces were given.