A satellite antenna positioning mechanism based on spherical gear (PMSG) was presented, and its kinematics character was also researched. The kinematics model of PMSG itself and a satellite were established separately, and the PMSG kinematics model was established based on the kinematics models. Considering the characters of intersatellite communication, the kinematics characters of two middle orbit satellites were simulated and researched for example. Results of the simulation verified the theory model established above, and the direction rule and motors movement rule were acquired, which were the theory basis in intersatellite communication. Conclusions acquired can be the basis of the engineering applies of PMSG, and it can be beneficial to the other correlative applications.