The multiple corrugated diaphragm (MCD) coupling is a new flexible coupling developed based on the diaphragm and diaphragm disc coupling. Compared to traditional couplings, the MCD coupling has the advantages of high torque diameter, high torque weight, and high compensation capability. It is more suitable for high power speed and high power density working conditions. The MCD coupling is subjected to axial, angular, torque, and centrifugal force loads. The fatigue failure caused by alternating stress is the primary failure mode of the coupling. The fatigue life of the MCD coupling cannot be accurately calculated because of the complexity of the force in operation. Some theoretical simplifications can only obtain the approximate result. In this paper, a parameterized finite element model of the MCDs is established. A method for calculating the fatigue safety factor of the MCD coupling is proposed based on a modified Goodman curve to know the design of the MCD coupling. The feasibility of this method is verified by the fatigue life test of the coupling.