Based on the experiments conducting in Luancheng Agro ecological Experimental Station, Chinese Academy of Sciences, from March to June, 1995, the characteristics of radiation budget, energy balance, as well as evapotranspiration partitioning into canopy transpiration and soil evaporation in wheat field are analyzed. The results show that the ratio of the absorbed to the incoming short radiation in canopy soil system is varying with wheat growth stages. The value is 0 8 in the jointing, decreasing with the increase of leaf area index ( LAI ), and reaches the minimum of 0 75 in the booting. It then increases again and finally reaches the maximum of 0 86 with the appearance of ears and wilting leaves. The ratio of net radiation to incoming radiation enhancing with the growth stage can be distinguished by three periods. The value is 0 45 in the jointing, becomes 0 5 in the booting and finally increases to 0 57 in the milking. The experiments identify that with the increasing of LAI , the ratio of soil heat flux to net radiation decreases from 0 13 in the jointing to 0 06 in the milking. However the ratios of latent heat flux and sensible heat flux to net radiation all increase, sometimes the former is larger than 1 and the latter turns to negative. LE is shown the main component of energy balance in the system. From jointing to maturing, i.e., from April 1st to May 28th, total evapotranspiration ( E_t ) in field is 250 mm with 50 mm from underneath soil evaporation and 200 mm from canopy transpiration. The relative evaporation (E_t/E_p) tends to increase with the season, the average of which is 0 70. The value of evapotranspiration, 4 3 mm/d, based on aerodynamic energy balance method, is agreeable with that based on water balance method. The similar results of E_t/E_p and daily evapotranspiration are also found in Yucheng Experimental Station, CAS, locating in North China Plain.