To ensure the ground coverage performance, the antenna is set with a certain downtilt angle, and the rear lobe of the antenna points to the low-altitude space domain. According to the current low-altitude network spatial domain test, the radio signals in the low-altitude spatial domain are disordered and the overlapping coverage is high. Under the same RSRP level, the SINR of radio signals is lower than that of the ground. In addition, the service requirements of the low-altitude network are not clear. Therefore, the low-altitude airspace is covered according to the existing ground network planning method, and the return on investment (ROI) is relatively low. This paper proposes a new method for spatial coverage planning in low-altitude network, which uses the lens antenna step reduction method based on the antenna gain to ensure the coverage performance of the target low-altitude spatial domain meets the requirements.