When the centers of inner and outer surfaces of the concentric spherical surface dome and the gimbal joint of the airborne laser communication transmitting antenna are not coincidence, the influence of the asymmetry optical dome on communication beam far-field divergence angle is analyzed. The results show that, at a maximal communication beam far-field divergence angle of 54°, a K9 spherical dome with the external diameter of 200 mm and the thickness of 5 mm makes the communication beam far-field divergence angle expand to 5.27-6.46 mrad from 126 μrad. The communication beam far-field divergence angle variation purely introduced by the dome surface manufacturing precision is very tiny, and can be ignored compared with the variation introduced by the dome optical power. A lens with spherical surfaces is used to compensate the communication beam far-field divergence angle change, and the communication beam far-field divergence angle of the whole transmitting angle range is smaller than 600 μrad.