With ASCE standardized reference Penman-Montieth as benchmark reference evapotranspiration equation, two commonly used ETref estimating methods, namely Priestley-Taylor and Hargreaves, were evaluated, local calibrated and validated in different climate regions in China. The results showed that Priestley-Taylor and Hargreaves performed better for grass reference crop in humid and arid regions,respectively. But the error in ETref estimating is unneglectable, and its can not be applied directly to alfalfa reference crop without local calibration. The local calibrated Priestley-Taylor and Hargreaves performed better in different climate regions, and the accuracy was significantly improved for alfalfa reference crop. Both methods performed better on grass than alfalfa reference crop. Performance of Priestley-Taylor showed no significant difference in different climate region, and Hargreaves had higher precision in arid region.