Abstract: Based on rainfall data of routine stations in Zhejiang, NCEP reanalysis data, sea surface temperature (SST) and daily averaged OLR data, the diagnostic analysis on the continuous rainy and sunless weather happened rarely in Zhejiang province in the beginning of 2012 is made focusing on circulation feature and moisture and dynamic conditions. Comparing with the data of the same period in the past，the influence of SST anomaly on Ural blocking high and anomalous southerly wind over the South China Sea and the bay of Bengal is also discussed in the paper. The results indicate as follows. 1) Northwest airflow in the front of the Ural blocking high offers cold air to the continuous rain.The southwest warm and wet airflow from the South China Sea to China’s southeast coast is stronger obviously than that in average years and forms a shear line together with northwest airflow mentioned above in Zhejiang leading to upward motion of vapor convergence in this area.Stronger westerly jet enhances divergence at upper level, and height and location of divergence zone play a leading role in the rain intensity.2) Northward spreading of tropical OLR low-value area before the increase of precipitation is important for forecasting. Upward flow in therainy area and downward flow in the north side of the rainy area form vertically a configuration like“warm in the upper level and cold in the low level”, and warm and wet airflow is forced to be lifted and condensed by cold air cushion. 3) The Walke circulation is strengthened by the cold SST anomaly in the middle-eastern Pacific at equator and warm SST anomaly near Indonesia. The updraft of the Walker circulation transported northward is a part of southwest airflow during the continuous rain. In addition, the SST which is positive anomaly in the north Pacific and SST which is negative anomaly in the middle-eastern Pacific are perhaps the external forcing factor for the formation and continuance of the Ural blocking high.