Based on 205 stations daily precipitation datasets and the characteristic parameters of the Meiyu period in low-middle reach of Yangtze River from 1960 to 2004, the rainfall , the precipitation-concentration degree (PCD) and precipitation-concentration period (PCP) of rainstorm event were calculated to analyze their heterogeneous characteristics , mainly including spatial and temporal distributions. It is proved that the precipitation and day of rainstorm increase heavily，but the PCD and PCP do not have the notable change. One of the important reasons that the great drought and great flood is made heavier in the lower reaches of Yangtze River is resulted from adding the precipitation and PCP of rainstorm including spatial and temporal distributions.