Based on the NCEP, TBB and observation data, the study of a torrential rain along Meiyu front in Yangtze River during July 9—10, 2003 is made. The diagnostic results show that the torrential rain on Meiyu front developed under the favorable environmental fields to cooperate with synoptic systems between the upper, middle and low levels through the interactions of circulations among different latitudes. The direct influencing system of torrential rain is β convective system. But the influencing systems in two regions are slightly different. The structure of Meiyu front has unique characteristics apart from typical feature. The structures of Meiyu front are different in two areas and the diversities of complicating structures of Meiyu front are revealed.