By using conventional observation data, NCEP reanalysis data and Doppler radar data, the causes of two weak snowfall events covering most of Jiangsu province during Feb.9-10, 2014 were analyzed. The results suggest that the snowfall event on Feb.9 was mainly caused by the eastward movement of westerly trough in the mid-troposphere and the lifting of the southwest warm and moist air ahead of the trough over a cold air "cushion" in the lower layer, which consequently led to a stratiform snowfall event. However, the snowfall on Feb.10 was primarily due to the northeastward movement of the main body of the low-level cold air, the obvious decreasing of low-level wind speed over the western inland area, little change of wind speed along the eastern coastal area and the westward expansion of the convergence zone. The low clouds snowfall caused by the low-level upward motion within the convergence zone limited to a small horizontal scale, like the weak convective system. The numerical prediction products conventionally used in the operational analysis, such as EC, do not accurately forecast the two weak snowfall events, especially for the case on Feb.10. However, the snowfall event on Feb.10 is simulated fairly well by the WRF model.