对周边式对接机构的航天器进行了研究，在对接捕获过程中首次接触撞击点的确定问题。文中建立了三类可能接触区域的空间解析描述关系式，根据空间“点”投影的不变性原理，给出了确定可能接触点的数学方程，使原问题由三维空间问题简化为二维平面问题，其难度和复杂性都大大简化。最后，文中还给出了多组算例。 The spacecraft of the peripheral docking mechanism was studied and the problem of the initial contact with the impact point during the docking capture process was studied. According to the principle of invariance of the projection of space “point”, the mathematical equation for determining possible contact points is given, which simplifies the original problem from the three-dimensional space problem to the two-dimensional plane problem , Its difficulty and complexity are greatly simplified. Finally, the article also gives multiple sets of examples.