Abstract: The Kotoda-Bortan (K-B) model, used for estimating evapotranspiration, is modified. The estimates of evapotranspoiration on various surfaces from the modified model are compared with those from the Kotaoda model, Advection-Aridity model, Eddy-Correlation and Bowen radio methods, based on the data collected in the Yangtze Delta Field Experiment (1999) and the Huaihe River Basin Energy and Water Cycle Experiment (HUBEX, 1998). The results show that the evapotranspiration estimates from the modified model are very close to those from the Eddy-Correlation and Bowen radio methods both for instantaneous and daily emtimations. The modified model has the following advantages: (1) the necessary input data are limited to those easily obtainable from routine meteorological observation, remote sensing technique and geographical information system; (2) it can be used to estimate evapotranspiration not only from arid and semi-surfaces, but also from wet and vegetated surfaces; (3) the results can be given as digitized square-grid maps. Using this model, we estimated evapotranspiration on various surfaces in the Yangtze Delta region (118° – 123° E, 28° – 33° N) in 1995, and the regional average of evapotranspiration is calculated by the weight mean method .