Abstract: Based on 14 samples of the weather events affected by the easterly wave occurred in Jiangxi province, the structure of the easterly wave were analyzed. The effect of the easterly wave on the ascending motion, temperature field, specific humidity field and stability were stud- ied based on upper air sounding and NCEP reanalysis data. Results show that there are ascending motion in the front of the high-level easter-ly wave above 500 hPa and weak ascending motion in the front of the deep easterly wave. Convection in front of the trough occurred in the afternoon. Convection in large-area occurred in the divergence of saddle field on 200 hPa. The thunderstorm is caused by the convergence of southeast flow in the back of the middle and low-level easterly wave and the deep easterly wave. Large-area convection occurs in the divergence that is in the south of South Asia High. The easterly wave provides the favorable environment condition for convection. In summer, the lower atmosphere is high in temperature and humidity. With the easterly wave moving forward west, there are cold disturbances in the middle- and upper atmosphere and increased specific humidity disturbances in the lower atmosphere. The places favorable for convective development are in the front of the high-level easterly wave and the deep easterly wave, and behind of the middle and low-level easterly wave and the deep easterly wave. The high-level easterly wave has the biggest cold disturbance and higher probability of Thunder Wind. The middle- and low-level easterly wave has weak cold disturbance and the type of the convection is mainly short-time strong rainfall.