As global warming intensifies, the increased frequency of heatwave events has potentially serious implications for human health, the stability of ecosystems, and the sustainable economic and social development of human societies. Moreover, the majority of existing studies on heatwaves in China has focused primarily on their overall spatial and temporal characteristics. However, our understanding of how heatwaves change across different geographic regions, particularly in relation to drought gradients, is clearly still inadequate. As a result, in this study, we analyzed the hourly 2m surface temperature data from ERA5-Land for the period from 1980 to 2020 to identify heatwave events using the relative threshold method and analyzed the spatio-temporal characteristics of the frequency, duration, and intensity characteristics of heatwaves in the seven geographical regions and different aridity zones. The results showed that (1) During the period 1980-2020, there was a significant increase in the frequency and duration of heatwaves. The rate at which heatwave intensity increased was faster, but this was not statistically significant. The characteristics of heatwaves differed significantly between regions. The frequency and intensity of heatwaves show a spatial pattern of "high in the northwest, low in the central, and high in the southeast," while the duration decreases from the southwest to the northeast. (2) The frequency and duration of heatwaves increased significantly in all seven geographical regions, with the fastest growth occurring in South China and the slowest in Northeast China. Meanwhile, heatwave intensity increased significantly in South, Central, North and Northwest China, with the fastest growth occurring in the latter. (3) There were significant differences in the frequency, duration and intensity of heatwaves across the drought gradient. The frequency and duration of heatwaves increase significantly across the drought gradient, while the intensity of heatwaves increases significantly in arid and extreme arid regions. Arid regions experience high frequencies and durations of heatwaves, while extreme arid regions are characterised mainly by high intensity. In contrast, arid sub-humid areas typically have a low frequency and short duration, as well as weak intensity. The results of the study revealed the spatial heterogeneity of heatwave characteristics in the context of climate warming and provided a scientific basis for accurately assessing the multifaceted impacts of heatwaves on ecosystems and human social life and for formulating effective response strategies. In addition, the results offer valuable insights for developing targeted regional risk management approaches and formulating differentiated heatwave prevention and adaptation strategies that address the unique vulnerabilities of each region.