The N-type double disc coupling has the characteristics of simplified structure and no need for lubrication. It is the main connecting component between the aircraft engine and the main reducer, mainly used to transmit torque and motion, and must withstand high speed, complex load conditions and comprehensive deviations between the transmission shaft systems. Under complex working conditions, the coupling can not only compensate the misalignment between the transmission shafting, but also produce various deformations, which are closely related to the stiffness of the coupling. Taking the N-type double disc coupling as the research object, strength calculation and analysis of the influencing factors of stiffness were carried out, and the stress distribution law of the profile under complex load conditions and the influence law of size parameters on stiffness were obtained. The effectiveness of the computational model was verified through experiments, providing theoretical reference for the design and optimization of double disc couplings.