Extreme high temperature (EHT) events are among the most impact-related consequences related to climate change, especially for China, a nation with a large population that is vulnerable to the climate warming. Based on the latest Coupled Model Intercomparison Project Phase 6 (CMIP6), this study assesses future EHT changes across China at five specific global warming thresholds (1.5°C–5°C). The results indicate that global mean temperature will increase by 1.5°C/2°C before 2030/2050 relative to pre-industrial levels (1861–1900) under three future scenarios (SSP1-2.6, SSP2-4.5, and SSP5- 8.5), and warming will occur faster under SSP5-8.5 compared to SSP1-2.6 and SSP2-4.5. Under SSP5-8.5, global warming will eventually exceed 5°C by 2100, while under SSP1-2.6, it will stabilize around 2°C after 2050. In China, most of the areas where warming exceeds global average levels will be located in Tibet and northern China (Northwest China, North China and Northeast China), covering 50%–70% of the country. Furthermore, about 0.19–0.44 billion people (accounting for 16%–41% of the national population) will experience warming above the global average. Compared to present-day (1995–2014), the warmest day (TXx) will increase most notably in northern China, while the number of warm days (TX90p) and warm spell duration indicator (WSDI) will increase most profoundly in southern China. For example, relative to the present-day, TXx will increase by 1°C–5°C in northern China, and TX90p (WSDI) will increase by 25–150 (10–80) days in southern China at 1.5°C–5°C global warming. Compared to 2°C–5°C, limiting global warming to 1.5°C will help avoid about 36%–87% of the EHT increases in China.