Abstract: The high-altitude platform station (HAPS) communication system has its unique advantages such as flexible deployment and large coverage. It can be widely used in a variety of communication scenarios in the future and has attracted the attention of researchers from various countries. Under the influence of stratospheric wind, HAPS will inevitably move within a certain range. In this paper, two modes of movement affected by path loss are discussed: vertical movement and swing movement. First, a more realistic ground coverage model is established and its calculation formulas are derived. Then, based on this coverage model, the handover probability of these two movement modes is calculated and analyzed, and is compared with the handover probability estimated using the existing coverage models. The results verified the validity of the proposed model.