The data from the SinoJapanese cooperational experiment on atmosphereland interaction processes at Shouxian in the Huaihe River Basin are used to analysis the variations of wind speed, air temperature, relative humidity, and radiation before and during rainy season. Some micrometeorological properties in the nearsurface layer are studied. The results show that there was obvious diurnal variation in both air temperature and relative humidity with one peak pattern in dry season. With the onset of rainy season, the air temperature decreased, relative humidity increased, wind speed fluctuated significantly, and the diurnal variation of meteorological elements became less obvious. It is clearly shown that the latent heat flux was far larger than the sensible heat flux over the middle of the Huaihe River basin. The clear variation trends of micrometeorological elements in dry and rainy season have certain indicative significance for forecasting the beginning and ending of rainy season.