Abstract: The mission of lunar detailed survey, lunar polar relay and lunar polar region landing will be completed in the subsequent lunar exploration project. Because of the poor communicate condition between the earth and moon polar region, a relay satellite will be launched and put in the proper orbit to set up the communication ability. An inclined and elliptical lunar orbit with frozen eccentricity and orbit period of 12 hour is selected as relay orbit after comparative analysis of different relay orbits, trajectory design of relay satellite and lunar polar region exploration mission. The results show that the relay satellite can fly more than ten years in the orbit without orbit maintenance. During the two thirds of one orbit period the relay satellite can communicate with the rover landing on the lunar polar region, which will provide reference for engineering implementation.