After detailed analysis of the weather pattern of torrential rainstorm in Shanghai on August the 5th 2001,it is pointed out that the main reason of ″0185″ tropical depression can maintain steadily in the strong subtropical high is its deep structure.And the break of subtropical high is the key inducement of pattern′s following evolvement.The western high′s north northwest stream at its north side flows into the tropical depression,which makes the strong convection among the tropical depression developing rapidly and continuously.Furthermore,the eastern high′s weakening is the main inducement of the ″0185″ tropical depression′s sudden eastward movement.