In recent years, droughts and floods have occurred frequently in the Poyang Lake Basin, and the original water balance has been broken. Therefore, it is of great strategic significance to carry out research on potential evapotranspiration and drought characteristics in the Poyang Lake Basin under climate change. Reference evapotranspiration (ET₀) is an important indicator for evaluating the allocation of water resources in the region and calculating the drought index. This paper takes Poyang Lake basin as the research area, relies on statistical downscaling models, selects daily observation data, global climate model data, and reanalysis data from the US Environmental Center. Relying on the genetic algorithms to construct a model set. The temporal and spatial evolution characteristics of the potential evapotranspiration and Drought Index (DI) of the basin under the future climate context are estimated. The results show that the genetic algorithm's model set has a better simulation performance than any single climate model and equal weight model set. Under the two scenarios of RCP4.5 and RCP8.5, the ET₀ in the Poyang Lake Basin shows an upward trend. The first major cycles of ET₀ change are 20 years and 4 years, respectively. The future spatial change characteristics of ET₀ in the basin are characterized by high in east and low in west. From 1961 to 2010, the interannual change of the DI in the Poyang Lake Basin showed a rising trend. It was high in summer and autumn and low in spring and winter. Spatially, the south and southeast of the Basin were the high value areas. Under the RCP8.5 scenario, the DI of the basin shows a significant upward trend in the interannual period. Autumn is a key period for preventing drought risks in the river basin. Eight years is the first major cycle of annual DI change in the Basin. The central and eastern regions of the Poyang Lake Basin will be key areas for future drought risk prevention. This study provides a reference for understanding the impact of climate change on potential evapotranspiration on a regional scale, and at the same time provides decision support for government departments to scientifically respond to possible droughts in the Poyang Lake Basin in the future.