Abstract: Based on queuing system and according to concurrency characteristics of comprehensive inquiry system when adopting database server,multi-server hybrid M/M/S/C queuing model was set up.Taking EMS memory limits of the server into account,optimal model was established under constraint of probability no more than metric.To conclude,the authors evaluate the simulation results after simulation is processed to this system.

Key words: concurrent inquiry, queuing theory, M/M/S/C model