Severe high-temperature leads significant risks of human health under the highly population concentration and climate change. The thermal sensitivity to high temperature is needed to be quantified associated with different population characteristics. Thermal condition was quantified by universal thermal climate index (UTCI) and thermal sensitivity was identified by thermal sensation votes (TSV), thermal comfort votes, and thermal unacceptability votes based on 667 questionnaires in Beijing, China. This study designated four indicators, i.e., neutral temperature, neutral temperature range, tolerance temperature, and tolerance temperature range to analyze the effects of individual characteristics on thermal sensitivity. A one-way ANOVA was used to identify the effects of long-term adaptation and psychological factors. Results showed that: (1) Older residents had a higher neutral temperature, narrow tolerance temperature range, and lower tolerance temperature of 1.2 degrees C UTCI than younger residents. (2) People with chronic disease had a narrow tolerance temperature range and lower tolerance temperature of 1.3 degrees C UTCI than healthy ones; (3) The proportion of people who voted strong thermal sensation (TSV >= 2) rated the highest in building areas, while the proportion decreased 31.6% in spaces with dense trees; (4) Residential history and city attractiveness had significant impacts on mean thermal sensation votes and mean thermal comfort votes, excluding the effect of thermal stress level. This study provided useful implications of specific adaption for summer extreme heat according to different population characteristics.