Abstract：In order to obtain the accurate estimation and prediction of reference crop evapotranspiration(ET0)in the absence of meteorological data, a nonlinear autoregressive exogenous inputs(NARX)model was constructed to predict ET0 in Panzhihua station. Taken the daily ET0 calculated by the Penman-Monteith model as the prediction standard values, the NARX models with 11 different combinations of meteorological factors was established by taking the daily maximum temperature, daily minimum temperature, sunshine hours, wind speed and relative humidity as the input parameters of the model. The calculation results of NARX models were compared with that of Hargreaves-Samani model, Irmak-Allen model, Makkink model and Priestley-Taylor model. The results show that the discrepancy of simulation performance is obvious for NARX model with different input meteorological factors. Among them, the RMSE, MAE, MBE of NARX-1 model is 0.425 mm/d, 0.320 mm/d, 0.069 mm/d, respectively, and the NSE is 0.920, GPI ranking the 11th in GPI with the worst simulation accuracy. NARX-9 model which is based on wind speed has the highest accuracy that RMSE, MAE, MBE is 0.285 mm/d, 0.237 mm/d, 0.019 mm/d, respectively, and the NSE is 0.964 and GPI ranks the 1. When inputting the same climate parameters of temperature and sunshine hours, the simulation accuracy of NARX-4 is better than that of Irmak-Allen, Makkink, Priestley-Taylor model. While, if inputting parameter is only temperature, the simulation accuracy of NARX-7 is better than that of Hargreaves-Samani model. Therefore, the NARX model can be used as a recommended model for the calculation of ET0 with limited meteorological data in southwestern mountain areas of Sichuan, and can provide a scientific evidence for accurate irrigation of farmland.
