It is difficult to make receiver locating in the center of the light spot for high-speed laser communication, which results in difficultly establishing a stable underwater optical communication links. Monte Carlo simulation statistics method is used to analyze the distribution of the received light intensity of laser photons transmitted in seawater, and then the light spot image at the receiving end is sampled and analyzed through experiments, and the relationship between the receiver position and the received light intensity is obtained by curve fitting. The simulation and experimental results show that the received light intensity distribution is still approximately Gaussian distribution after 25 m underwater transmission. Based on the nonlinear estimation algorithm (extended Kalman filter) under the basic state control feedback theory, the distance between current position and position of the maximum light intensity spot is estimated according to received light intensity, and active tracking alignment between the receiver and the spot center is achieved by feedback algorithm. The simulation results show that the alignment error of the receiving end is less than 2 mm and the receiving efficiency is more than 98% after alignment.