This work investigates the possible future changes and impacts in spatiotemporal variation and regional features of multivariate compound heatwaves (CHWs) in China using the latest Universal Thermal Climate Index from the Coupled Model Intercomparison Project Phase 6 simulations (CMIP6). Results indicate both strong CHWs and extremely threatening CHWs in China are projected to increase substantially in both frequency and spatial extent under different future climate scenarios while with discernible regional disparities. The more severe global warming is, and the greater the extremity of the heatwave events is, the faster the increase in CHWs is. These findings are derived from the CMIP6 projections calibrated using the robust empirical quantiles method. Climate change causes more areas and people to be exposed to CHWs. Notably, the population exposure to dangerous CHWs will increase significantly in northwest China and will appear in northeast China after the mid‐21st century under the high emission scenario. Plain Language Summary: Extreme multivariate compound heatwaves (CHWs) may have devastating impacts on human health and have attracted significant societal attention. We explored the possible future changes in dangerous multivariate CHWs in China based on the latest Universal Thermal Climate Index (UTCI) from the Coupled Model Intercomparison Project Phase 6 simulations (CMIP6) project. Results show that the CMIP6 UTCI in China has a warm bias compared to the observations. A nonparametric quantile mapping using a robust empirical quantiles method is employed which can effectively correct this bias and is used to constrain future CMIP6 projections to reduce uncertainties. Two categories of dangerous CHWs are investigated in the current work, that is, strong compound heatwaves and extremely threatening CHWs. Results indicate an expected acceleration in the rate of CHWs and population exposure after the mid‐21st century, primarily driven by climate changes. Moreover, the rate of acceleration is found to be more pronounced for CHWs of higher extremities and in the context of the increased severity of global warming. Additionally, population exposure to extremely threatening CHWs will increase significantly not only in southeastern China but also in northwestern and northeastern regions. Our study highlights the critical importance of mitigating climate change to minimize the threat posed by dangerous CHWs to human populations. Key Points: A nonparametric quantile mapping method can effectively correct the warm bias in the latest Coupled Model Intercomparison Project Phase 6 simulations Universal Thermal Climate Index in ChinaThe increasing rate of compound heatwaves (CHWs) in China will accelerate with the increase in the event extremity and severity of warmingPopulation exposure to CHWs will increase significantly in northwest and northeast China in a warmer world [ABSTRACT FROM AUTHOR]