To improve the positioning accuracy and reliability of COMPASS, an analysis of the COMPASS has been performed; combination of technical experience of the foreign global satellite navigation system and the current release of technical information, we have designed COMPASS constellation, by satellite visibility analysis and a variety of DOP's numerical comparison of the different design options, we can prove the COMPASS constellation program can meet the needs of the global satellite location, especially in China and its surrounding areas, the designed COMPASS have more precise positioning compared to other global navigation system.