Abstract: The energy change characteristics and closure rate of cropland ecosystem are of great significance to the study of the dynamic and thermal structure of the atmospheric boundary layer over the cropland underlying surface and the improvement of the parameterization of land-atmosphere interaction of the regional numerical model. Based on the observation data of sensible heat flux, latent heat flux, soil heat flux and radiation flux in flux observation system in Shouxian National Climatological Observatory from July 2007 to April 2013, this paper studies the energy change characteristics and closure rate of cropland ecosystem in Huaihe River Basin. Results show that the daily variation characteristics of sensible heat flux, latent heat flux, Bowen ratio and soil heat flux are all of unimodal distributions, and the annual average Bowen ratio is 0.43, which shows that latent heat flux of underlying surface is dominant. The daily variation amplitude of each radiation component and net radiation are quite different, among which the variation amplitude of downward shortwave radiation is the largest, while that of downward longwave radiation is the smallest. From the perspective of monthly variation, they all present the single peak distributions. The total average of the surface upward longwave radiation is the largest, while the upward shortwave radiation is the smallest. The linear regression line of effective energy and turbulent flux is basically below 1:1, which indicates that there is no closure of energy and the turbulent flux is less than the effective energy. The average energy balance ratio is 94%, which is the largest in May and the smallest in December. The energy closure rate in spring is the largest, followed by that in summer, and it is the smallest in winter. In general, the energy closure rate of cropland ecosystem in Huaihe River Basin is relatively high, and the data in flux observation system is reliable.