Evapotranspiration is an important and complicated part of the hydrological cycle, of which accurate measurement and computation is needed for an adequate management of agricultural water resources. In this paper, latest advances in methods for measuring and estimating actual ET at a plot and regional scale. In the past decade, the techniques of TDR, Micro-Lysimeter and Eddy covariance at plot scale and remote sensing technique for estimating regional ET have been more and more widely used. With the development of automation and sensor manufacturing techniques, ET measurement has been greatly improved in accuracy. In calculating actual ET, simple ET models, such as Priestley-Taylor model, Penman model and Penman-Monteith model, are more often employed. But in research, workers have put more and more attention to Shuttleworth-Wallace-model-based multi-layer models, which can be used to simulate ET of canopies and substrates of different types. Great progress has been made in remote sensing estimation of regional ET with several regional ET estimating approaches developed. CRAE models as an important method to estimate regional ET has found more and more recognition and application.