Based on data from 10 rainfall observation stations, hydrology statistics and correlation methods were used to analyze the spatial distribution, annual distribution and inter-annual variation of the annual average rainfall in the Lishui river basin. The general trend is that the annual average rainfall reduces gradually from the upper to the lower reaches of the River Basin, from the north-western mountain-hilly area to the south-eastern lakeside plain. Meanwhile, there is a connection between rainfall and elevation: as elevation lowers every 100 m, the annual rainfall reduces 137.76 mm; besides, the seasonal variation is quite evident, and the distribution throughout the year is uneven, with the uneven coefficient reaches 0.25. What’s more, obvious inter-annual variation do exist, inter-annual variation in the middle and the lower reaches are greater than that of the upper one. Wet-dry periods during raining years last long and change greatly. It is recorded that the longest period being consistent wet is three years and four for being consistent dry.