Building reliable, practical, economical and convenient parking garages is a basic measure to solve the problem of difficult parking in some built-up areas in cities. Two kinds of building stereo garage design schemes were proposed and their economic indicators were given. The operation modes of the car elevators were simulated by MATLAB programming, the working rate of the stereo garage with 1, 2 and 3 car elevators under three different strategies including storage priority, picking-up priority and standing-by was calculated, and the optimal operation strategy was given. Through the analysis of the traffic flow data of a residential area and the running time of the car elevator from the MATLAB programming simulation, the probability distribution form of the traffic flow and the running time of the car elevator was obtained. Based on the queuing theory, combined with the probability distribution form of the traffic flow, the working speed of the stereo garage under the optimal control strategy and the users' acceptable waiting time, the optimal number of car elevators for the stereo garage scheme was determined. The research results show that when the garage is dealing with continuous traffic, the standing-by strategy is the optimal operation strategy. When responding to the local traffic flow under the optimal operation strategy, the configuration of two car elevators can meet the need of users to access the cars and the four parameters of the average queue length, average queuing platoon, average length of stay, average waiting time of the queuing system are also acceptable.