The stable operation of navigation satellite constellation is related to national economy and national defense security. The failure of any one or two satellites has little impact on the overall performance of the global navigation satellite constellation, and the availability of the navigation constellation decreases with the increase of the number of failed satellites. First, a typical medium earth orbit Walker-δ 24/3/1 constellation configuration was designed. Second, the service performance of the navigation constellation under different failure modes was analyzed. The weaknesses of the constellation were identified in combination with the availability data of the navigation constellation. Then, the overall performance of the navigation constellation after the low earth orbit satellite constellation compensates for the failure of the medium earth orbit satellite constellation is analyzed. The simulation results show that the failure of 5 global navigation satellites will reduce the availability of navigation constellation to 71%, and the hybrid navigation constellation can recover the availability to more than 97%. The orbital altitude and inclination of low orbit satellites affect the overall performance of the hybrid navigation constellation. The research results can provide reference for the demonstration of hybrid navigation constellation scheme.