Abstract: Based on the data of hourly precipitation and monthly average temperature from June to September of 7 national meteorological stations from 1980 to 2015 and hourly precipitation of 63 automatic weather stations(AWS) from 2008 to 2015, and the monthly average reanalysis data of ECMWF ERA-interim, the temporal-spatial distribution of short-time heavy rainfall of flood season in Taiyuan was analyzed, and the influences of the variation of urban heat island (UHI) intensity and the anomalies of circulation background were studied by using climatic trend parameter, M-K test, composite analysis and t-test methods. The results showed that the days of short-time heavy rainfall had obvious inter-decadal variation in recent 36 years with annual mean days of 3.3 d; the days of short-time heavy rainfall increased rapidly and decreased sharply from June to September with concentrated intensities mainly of 20-30 mm/h; the ≥ 40 mm/h heavy rain concentrated between the late of the first ten-day period of July and the first ten-day period of August; 16:00—17:00 was the most active period in a day for short-time heavy rainfall. There were more short-time heavy rainfalls in the urban area than that in the mountainous areas, mainly in July. The observation from the automatic weather stations in Taiyuan during 2008-2015 found that the short-time heavy rainfall in Taiyuan extended rapidly to all areas of Taiyuan from June to July, and in August shrunk to eastern areas, and in September decreased sharply and occurred dispersedly in eastern areas. The enhanced intensity of UHI in recent 36 years and the southward expansion of urbanization maybe the influential factors for the increase of short-time heavy rainfall in southern urban area in Taiyuan. In July of the more short-time heavy rainfall years, there was a ridge in west Sibarian, and a trough in Lack Baikal, the geopotential height was lower in north China on 500 hPa with stronger cold air, and the western pacific subtropical high leaned significantly to west compared with the less years, therefore the CAPE values were higher in Taiyua, then the short-time heavy rainfall occurred more frequently; The less years were just the opposite. This study can provide references for forecasting and research on shot-time heavy rainfall and urban disaster prevention and relief.