By using NCEP/NCAR reanalysis data, ERSST.V3b sea surface temperature data from NOAA and the precipitation data of 66 observational stations since 1971 in Zhejiang province. The correlation between the statistical features of the abnormal atmospheric circulation as well as the tropical sea surface temperature and the more than normal precipitation in November over Zhejiang province were analyzed. Furthermore, the mechanism for anomalous precipitation in November, 2015 was studied. Results show that the precipitation in November, 2015 is due to the anomalous heavy decadal background, meanwhile, the Arctic Oscillation is positive and the intensity is abnormally stronger, the meridional circulation at mid-high latitude is weaker than normal, and the West Pacific subtropical high is enhanced and more westward than normal, leading to the extremely anomalous precipitation in November of 2015. Statistical analysis reveals that precipitation in November is mainly related to the geopotential height in wide ranges from Balkhash to Baikal and strength of the West Pacific subtropical high. Finally, El Niño is proved as a key external forcing factor influencing the precipitation of November in Zhejiang province. The Nino3.4 index in November of 2015 reaches the highest which result in the flooding over Zhejiang province.