In the context of global warming, the impact of climate change on water resources is becoming increasingly significant and is thus drawing more attention. As a main component of the hydrological cycle, potential evapotranspiration (ET_0) represents the maximum possible evaporation and is the rate of evaporation that would occur under given meteorological conditions from a continuously saturated surface. ET_0 is essential for scheduling of irrigation system running times,preparing input data for hydrological models used in water balance studies,and assessing the hydrological impacts of the changing climate. Therefore, the trends of the changes in ET_0 and its dominant factors across different regions of the world have been studied by many researchers in recent decades. Despite the global warming, decreasing trends in ET_0 have been detected in several countries, including the United States, Russia, India, China, Australia, and New Zealand. Decreasing sunshine hours, declining wind speed, and increasing relative humidity have been considered to be the main causes of the decreasing ET0.Analysis of the linear trend of the time series is frequently used in climate change research. The linear trend can reflect the overall trend of climate change over a time period,but it cannot describe the undulating character of climate change over a long time period. Thus, the characteristics of interdecadal turning of climatic factors, including air temperature, precipitation, and solar radiation, have become a topic of concern for many researchers worldwide. Thorough exploration of the interdecadal turning of ET_0 trends can lead to a better understanding of the evolution and abrupt changes of ET_0 related to climate change. Based on the FA056 Penman-Monteith equation,interdecadal breakpoints in ET_0 trends were studied using Tome and Miranda's climate-trend turning discriminatory model for 580 meteorological stations across China during 1971-2010. Differences in the trends and determining factors between the before and after breakpoint periods were also analyzed. The results showed that annual average ET_0 decreased significantly (-2.46 mm/a) before the 1990s but increased significantly (1.57 mm/a) after the 1990s across China. This phenomenon was closely related to the interdecadal breakpoints in the trends of four meteorological factors affecting ET_0 variations. The decrease in ET_0 that occurred before the 1990s was attributed to a larger absolute value of the negative contributions caused by decreasing wind speed and sunshine duration compared to that of the positive contribution caused by increasing air temperature. After the 1990s, positive contribution from the air temperature and relative humidity increased due to the more intensive warming and climatic aridity across most of the areas in China and exceeded the smaller absolute value of the negative contribution from the wind speed and sunshine duration, causing the increasing trend in ET_0. The interdecadal breakpoints existed at more than 80% of the meteorological stations across China, and there were differences between the pre- and post-breakpoint distribution patterns. Before the 1990s, wind speed and sunshine duration were the determining factors for most stations in North China and South China, respectively. After the 1990s, the number of stations with air temperature or relative humidity as a determining factor increased,especially in Northwest China,the Tibetan Plateau,and some parts of the southeastern coastal area.