Based on the mixed and heterogeneous constellation characteristics of the COMPASS navigation system, the weighted dilution of precision (WDOP) is applied to analyze the positioning geometric strength, and the results are compared with the geometric dilution of precision (GDOP) of GPS and Galileo navigation constellation. Aiming at global and regional users, the difference between the positioning performances of various user groups are presented, indicating that the COMPASS constellation possesses remarkable advantages in both the visibility and the positioning geometric strength for regional users. The loss of the positioning performance under the circumstance of individual satellite malfunction of the COMPASS constellation is also discussed, and simulations show that the absence of GEO satellites has the largest impact on the China region.