Abstract:Compound heat waves which consider the effect of temperature, humidity, wind speed and radiation simultaneously, have a major impact on human health and ecological diversity. Based on the wet-bulb globe temperature (WBGT), this paper identifies the compound heat waves in China, and quantitatively analyzes the synergy between urbanization and the Western Pacific Subtropical High intensification on the compound heat waves in China. Results show that the total number of days, intensity and spatial coverage of China's compound heat waves increase gradually from 1979 to 2019, with a sharp increase after 2010 and the three indices for the compound heat waves in 2010 were approximately four times higher than that in the 1980s. It is also find that the synergy between the rapid development of urbanization and the intensification of the?Western?Pacific?Subtropical?High intensifies the compound heat waves in China. The early urbanization has contributed 9.2%, 12.5%, and 7.5% to the increase in the total number of days, intensity, and spatial coverage of the compound heat waves, respectively. During the same period, the Western?Pacific?Subtropical?High has a positive contribution of about 30% to the three heat wave indexes, and the contribution can be up to about 70% when the strengthening effect of global warming on the?Western?Pacific?Subtropical?High is considered. The above results suggest that the synergy between the rapid urbanization and the enhanced Western?Pacific?Subtropical?High under the background of global warming can explain more than 80% of the China's compound heat waves which have jumped sharply in 2010s.