Reference evapotranspiration (ET_0), an indicator of global climate change, makes different responses to the meteorological variable at different altitudes. The present study, based on the basic data of 38 meteorological stations in different altitude areas in Sichuan province, investigated the attribution of the change of the daily ET_0 and used the FAO-56 Penman- Monteith method to calculate its reference evapotranspiration ET_0 for the period 1970-2016 for a total of 47 years. The Sliding T test was used to identify the breakpoint. Sensitivity Analysis and contribution rate analysis were also used to detect the meteorological elements in response to ET_0 at different altitudes. An insignificant increasing tendency of ET_0 was observed on the time scale. 1998 was a mutation point of the sequence, with a significant downward trend in 1970-1998 and a significantly upward trend after 1998. The ET_0 in partition Ⅰ (low altitude), Ⅱ (middle altitude) and Ⅲ (high altitude) increased first and then decreased with altitude. In the meteorological elements, the relative humidity (RH), daily average temperature (t), sunshine duration (S) and daily mean wind speed (WS) was the closest meteorological factors to ET_0. Among them, the trend of RH, S, WS was changed in 1998, while t maintained an increasing trend. The sensitivity analysis results showed that RH had the greatest response to ET_0 while S had the minimum. The contribution of WS, S, RH to the change of ET_0 turned in 1998 with a negative contribution in 1970-1998 and a positive contribution after 1998, while t was a positive contribution to the change in ET_0 all the time. In the regions below 3 000 m, the ET_0 was mainly affected by WS, while in those areas above 3 000 m remainly affected by t and RH. The results of this study will help to understand the response of meteorological elements to the changes of ET_0 so as to provide scientific basis for the water resources planning and management.