Abstract: To address the data output delay problem in the high-precision tightly coupled inertial navigation system/celestial navigation system (INS/CNS), a multi-model time delay compensation method based on the extended Kalman filter (EKF) is proposed. This method enables real-time calibration of navigation data and offers a novel approach to resolving measurement delays and irregular output intervals among subsystems. The experimental results show significant improvements: the positioning error in latitude and longitude is reduced from 50 m to 10 m; the heading angle error is reduced from 8′ to 0.5′; and the velocity error in eastward and northward celestial directions is reduced from 0.3 m/s and 1.5 m/s to 0.01 m/s and 0.1 m/s, respectively. Furthermore, Monte carlo simulations confirm that the positioning error influence factor remains within the specified range, validating the robustness of the system performance.