The angular accuracy of ship borne theodolite is significantly affected by its own shafting error, inertial navigation attitude error and unknown ship deformation. In order to reduce the influence of these factors, the optical axis spatial calibration method based on airborne light source simulating stellar theodolite is proposed. The proposed method effectively combines star sensor and carrier phase differential technique of global position system(GPS). Two unmanned aerial vehicles are used to carry out accompanying flight, which make two airborne light sources appear in the field of view of calibration telescope. Thus, two high precision base lines are built, and the calculation of optical axis space pointing of calibration telescope is finished by using double-vector altitude determination. Finally, the calibration and calculation of optical axis in the theodolite system accurately pointing at horizontal coordinate system are realized. The simulation results show that the optical axis space pointing calibration accuracy is better than 10″ by optimizing the parameter configuration. This method can realize the accurate calibration of theodolite optical axis space under the dynamic condition of the sea.