An analytic dynamic trajectory generating algorithm based on real flight data interpolation was proposed for INS/GNSS integrated navigation simulation, in order to solve the problem of generating high-precision simulated signals of gyros and accelerometers in a strapdown inertial navigation system. Accurate piecewise analytic expressions of angular rates, angular increments and specific force integral increments in body frame were obtained on the basis of the spline function interpolation for the vehicle′s attitude, position and gravity data in the earth centered inertial frame. The simulated signals of gyros and accelerometers were coincident not only with the vehicle′s kinematics and dynamic characteristics, but also with the characteristics of post-processed GNSS′s pseudo-ranges and their rate measurements. The influence of the lever arm effect of an inertial measurement unit was also simulated. A constrained analytic quaternion interpolation algorithm was proposed under the restrictive condition in which the norm of the interpolated quaternion should be 1. Based on the real flight data of an unmanned aerial vehicle, it is proved that the accuracy and the effectiveness of the proposed algorithm can meet the requirements of dynamic simulation of integrated navigation. The algorithm can also be used in other simulations, such as high-precision high-dynamic navigation and rigid body motion control, in which the simulated sensor signals in angular and linear motion are needed.