Abstract: For the deficiency and difficulty of traditional simulation applied to designing a queuing system, this article addressed that it can be improved by using a new simulation technique named inverse simulation in Discrete-Event System. Taking a Emergency Ambulance Services (EAS) system (one station) as an example, the method and process of inverse simulation for designing this system's configuration is introduced. Finally the designing consequence is validated with forward simulation, which shows the feasibility and efficiency of new technique in solving this sort of problems.