Abstract: The immune algorithm is an intelligentized heuristic algorithm that imitates the high-evolvement of the organism and the complicated immune system. The vehicle scheduling problem with fuzzy demands (VSPFD) is a variation of vehicle scheduling problem (VSP),which is a typical NP-hard problem. By means of a new coding method, and the adaptive mechanism of crossover and mutation, an improved immune algorithm(IIA) is proposed to solve the VSPFD. Simulation results show the effectiveness of the proposed algorithms for solving the problem of VSPFD.