With the rapid development of the times, traditional communication methods such as microwave communication have been difficult to meet the needs of high-speed and high-capacity communication. People begin to look for new communication technologies to replace the existing communication methods. Laser communication has the advantages of high bandwidth, small terminal volume and good security. In the process of space laser communication, the coupling of space light to single-mode fiber is one of the difficulties. In the process of practical application, external jitter (atmospheric turbulence, platform vibration, etc.) makes the focus spot offset from the end face of the optical fiber, greatly reduces the energy coupled into the single-mode optical fiber, and seriously affects the communication quality. Applying the mature optical fiber communication technology to space laser communication can not only improve the transmission rate of the link, but also improve the communication quality and simplify the system composition. Based on laser nutation, aiming at the problem of space optical coupling into single-mode fiber in space laser communication, this paper analyzes the influence of alignment error on coupling efficiency. The lateral deviation has the greatest influence. In this paper, a laser nutation coupling system model based on the fast mirror is built. The model is based on the principle of mode field matching. The nutation signal of the nutation fast mirror is used as the modulation signal, and the optical power output by the photodetector is used as the feedback for calculation. The fast mirror is controlled in real time to compensate the transverse deviation. The algorithm flow of laser nutation is described, the simulation model is built, and the feasibility of the algorithm is verified. Based on different algorithm parameters such as nutation radius and convergence step, the relationship between parameter value and algorithm performance is obtained. © 2021 SPIE.