In order to achieve automatic discovery of simulation resources in a SAC( Sharing Among Clouds) simulation environment, resource request description method and discovery algorithm were studied, and scenario driven resource discovery method was proposed. By using extended MSDL (Military Scenario Definition Language) as resource request scheme and DM&TF (Double Mapping and Triple Filtering) as resource discovery algorithm, resources for cloud simulation can be automatically discovered. Analysis showed scenario driven resource discovery method was able to automatically discover large numbers of resources needed for a simulation in pragmatic level, which is of great help for rapid configuration of simulation environment.