Based on the monthly rainfall data (June-September) in Nanjing City during 1951-2016 , this paper analyzed the longtermdynamic and variability of heavy rainfall in the flood season. Long-term dynamic results show that the occurrence frequencyof heavy rainfall in Nanjing has increased significantly over the past 66 years with an average increase of 0.31 times per 10 years.Among different sizes of heavy rainfall, the occurrence frequency weather of the torrential rain and the heavy torrential rain bothshow increasing trends and torrential rain weather increase greatly. Multi -year monthly sliding standard deviation have passedthrough the confidence level of 99% significance test, and the mutation of torrential rain weather show a significant decrease trend.The heavy rainfall weather tends to be concentrated during the flood season (July), and the monthly pattern of it tends to bestable. It coincides with the result of the multi-year monthly sliding standard deviation that the heavy rainfall weather variabilityshow a decreasing trend.