Abstract: Based on the hourly rainfall data set from the hydrological rainfall observational network, the features of the rain storm activity over the Tai Lake Basin and the Lixiahe Area during two periods of sustained torrential rain in June-July 1991 are analyzed. The results show that there are frequent rain storm activities over the two areas and the regimes of the rain storm activity are different between the two areas. The rain storms move mainly eastwards with stationary sometimes. The rainfall of rain ctorm is a great part of the precipitation for the period of sustained torrential rain and takes an important role in the formation and development of the torrential rain flood and waterlogging. The rain storm activities relate to the mesosynoptic sxstems such as the mesoscale shear line, the mesoscale convergence line and the mesoscale convergence center.