Aiming at the shortcomings of long queues and low efficiency of vehicle queues in the process of plane mobile stereo garage parking space allocation. By analyzing the queueing process of the vehicle and the time characteristics of the vehicle entering and leaving the garage, we propose a parking space allocation method based on the probability characteristics of the vehicle entering and leaving the garage. The parking space allocation simulation program under the probability of near allocation and outbound storage is written separately, and the average waiting time of the customer, the average waiting queue length, the average service time and the idle probability of the carrier are used as the evaluation indexes of the service efficiency of the stereo garage, and the two schemes are compared and analyzed. The simulation results show that the parking space allocation with the probability of entering and leaving the garage is better than the nearest allocation principle. This method can effectively improve the service efficiency of the stereo garage.