Considering the difficulties in construction and on-site processing of outdoor three-dementional calibration target, and the low precision of chessboard target, a new camera calibration method based on circular markers is put forward to meet the high-precision of panoramic camera for deep space explorations. A large number of circular markers are distributed on the target in matrix form, one of which is taken as the origin of world coordinate system. Based on the camera model and collinearity of object point, camera origin, and image point, the optimal camera parameters are obtained with nonlinear optimization method, which use minimizing projection error as objective function. Experimental results show that this method with higher precision and better robustness is feasible and effective. The accuracy is better than 0.3 pixel. The distortion model is suitable and the projection error is better than 0.07 pixel.