A strapdown inertial navigation trajectory generator based on a six degree of freedom flight model was established to address the issue that traditional trajectory generators cannot fully reflect the actual motion characteristics of aircraft.Firstly, the six degree of freedom flight model and coordinate system in inertial navigation solution were introduced, and a six degree of freedom flight mathematical model was established. Secondly, convert the trajectory data generated by the trajectory generator into a navigation coordinate system through coordinate transformation. Then, a method was proposed to obtain the velocity increment using the strapdown inertial navigation inversion algorithm and to directly obtain the angular velocity using the trajectory generator. Simulation experiments show that the trajectory generator can truly reflect the motion characteristics of the aircraft, and the navigation accuracy meets the requirements, supporting the validation and simulation of the inertial navigation system algorithm.