Abstract: A key technology of γEMP as sorted simulator is the synchronous operating between the γsimulator and the EMPsimulator.This paper analyzes the requirement of the assorted simulator to the synchronous capability of γsimulator and points out that the time jitter ΔTγ in γsimulator should reach to the level less than half width at half maximum of γpulse. Then, the difficulties and the methods of improving synchronous capability of FlashⅠ γsimulator are analyzed and reseached. The synchronous capability and feasibility of Flash1A as the γsimulator　in the γEMP simulator system are discussed aslo.