Energy balance in the terrestrial ecosystem plays an important role in regional climate and water balance. By using the open鄄path eddy covariance and micrometeorological observation systems, turbulent energy fluxes and available energy were measured in a mixed plantation in the Xiaolangdi area in the North China during the growing season of 2012 (May鄄September). The diurnal and monthly variations of energy balance terms were analyzed, and energy closure and Bowen ratio were discussed. The results showed that the diurnal variation of energy balance terms were similar to that of net radiation, and the variation order of energy balance terms was net radiation >latent heat flux >sensible heat flux >soil heat flux. The time of keeping positives for energy balance terms in a day became shorter from May to September as energy balance terms were influenced by sunshine hour. The maximal net radiation occurred in June with a value of 418.5 MJ m-2