According to the application environment of deep space laser communication, this paper analyzes the key performance indicators in the communication link. After taking into account factors such as distance spot diffusion attenuation, pointing control accuracy attenuation, atmospheric attenuation, solar radiation, detector dark current noise etc., this paper determines the specific calculation method of communication rate and communication bit error rate. Through formula derivation, the impact of the transmitter telescope diameter (laser beam divergence angle) and pointing control accuracy on the maximum communication distance is analyzed, and numerical simulation is used to support and further analyze the constraint relationships between transmitter telescope diameter (laser beam divergence angle) and pointing control accuracy and proposed design methods for the design of deep space laser communication links. The performance of laser links in the scenarios of earth-moon space and earth-Mars space under the existing laser communication capabilities is further calculated.