The effect of atmospheric stability has been considered in calculating ET fromfields bv Penman-Monteith method.By introducing the equation of the lndex of Agreement,the effect on accuracies of ET calculations with and withotit adjustment of the stability havebeen examined.Results show that the. accuracy of the calculation by the revised equation is sharply reduced with the mean absolute error increased by as > 100%.Therefore,it is feasible to neglect the correction of atmospheric stability in calculating ET. The result is in agreement with the reference(2)conclusion.