Based on the heavy rain data from 9 stations along the coastal areas of the southern Fujian from 1961 to 2007, the characteristics of heavy rainfall are analyzed, and the 24hour Probably Maximum Precipitation (PMP) is calculated for the area by using the probability method and the hydrometeorological method. Results show: (1) In the coastal area of the southern Fujian, heavy rains mostly happen in spring and summer, and there were two dominating types: frontal rainstorm and typhoon rainstorm; even though in a homogenous region, the intensity and areas of heavy rains are random. (2) The calculated PMP with PearsonⅢ distribution is not reasonable unless the extraordinary heavy rains and their frequency are considered and calculated. In addition, the randomicity of rainstorms must be taken into account in order to insure the correctness of calculated results.（3）The chosen heavy rain model belongs to highefficiency precipitation, so PMP was calculated with the vapor magnification method. The calculated results, compared with the results of the probability method, are reasonable.