By embedding quantum bits into satellites, low-orbit quantum satellites enable highly secure communications, thus protecting information from eavesdropping and tampering. Currently, quantum-satellite resources are few, and two decision-making attributes of candidate quantum satellites are prioritized, i.e., service time and signal strength, to reasonably allocate the existing quantum-satellite resources such that the normal business requirements of end-users are satisfied. In this study, to minimize the interference of X-ray flares, a star-ground quantum-communication-link fading model under the interference of X-ray flares was constructed, and a quantum-satellite resource scheduling strategy based on a hybrid-immunity and simulated-annealing algorithm was proposed by combining the remaining service time of quantum satellites and their signal strengths based on three decision-making attributes, which were used as the objective function of the system model. The results show that the strategy offers better convergence stability and load balancing than the unimproved-immune and simulated-annealing algorithm, thus providing useful reference for the efficient utilization of quantum-satellite resources and the switching of low-orbit quantum satellites under the interference of X-ray flares.