To implement the astronomical observation on the moon, the thermal analysis and structure design of a 2D reflection mirror gimbal for the lunar based astronomy optical telescope were performed. The 2D rotary structure of reflection mirror was designed based on lightweighting method to reduce the load mass. Because an external rotor mechanism was used for the vertical shaft, the first order mode of the system along the emission direction was greatly improved. For a larger span in the horizontal shaft, a shaft system with one fixed end and another free end was adopted. Moreover, the clearance of deep groove ball bearings was designed rationally to eliminate the block of the rotary structure caused by temperature changes on the moon. In order to meet the high accuracy ，the reflection mirror gimbal used a worm gear and a step motor to drive the gimbal and to control the machining in a strict technology. In addition, an optics switch was used to achieve high accuracy position and make the accuracy of gimbal be better than 60″。 Experiments show that the first order resonant frequency of the system can reach 81 Hz along the rocket-firing track, the mechanism works well at -25 ℃ to +60 ℃ without stuck phenomenon and its direction accuracy is less than 60″. These results demonstrate that the system is characterized by high accuracy, high reliability and light weight.