Spacecraft pose estimation is an important technology for spacecraft to maintain or change its orientation in space. For spacecraft pose estimation, when two spacecraft are relatively far away, the depth information of the space point is less than that of measuring distance, so that the camera model can be seen as a weak perspective projection model. In this paper, a spacecraft pose estimation algorithm based on four symmetrical points of the spacecraft outline is proposed. Analytical solution of spacecraft pose is obtained by solving the weak perspective projection model, which can meet the requirements of the measurement model when there is a long measurement distance. Optimal solution is obtained from the weak perspective projection model to the perspective projection model, which can meet the measurement requirement when the measuring distance is close. The simulation results show that the proposed algorithm can get better results even though the noise is large.