To study the characteristics of summer thermal comfort and adaptation of naturally ventilated university dormitories in Changsha, 15 naturally ventilated dormitories of two universities in Changsha are investigated in this paper. Environmental parameters were recorded, and surveys were conducted on the thermal sensation and thermal adaptation behavior of the subjects. In total, 437 research data were collected. Based on temperature frequency method and weighted linear fitting method, the relations of indoor operating temperature with clothing thermal resistance, the predicted mean thermal sensation (PMV), and the actual mean thermal sensation (MTS) were determined. Results indicate that clothing thermal resistance negatively correlated with indoor operating temperature in summer. With the increase of unit operating temperature, clothing thermal resistance reduced by 0.019 7 clo. PMV was larger than MTS, and the higher the operating temperature was, the greater the difference between the two was. The corresponding acceptable temperature ranges of the two were 24.4 ℃~28.7 ℃ and 23.8 ℃~28.9 ℃, respectively. By using adaptive PMV model, the adaptive coefficient of the naturally ventilated university dormitories in Changsha was calculated to be 0.5, which is in great discrepancy with the prescribed values given in GB/T50785—2012 “Evaluation standard for indoor thermal environment in civil buildings.” The male and female research data were studied separately.As the unit operating temperature increased, the clothing thermal resistance of male and female reduced by 0.028 8 clo and 0.016 4 clo respectively. Male feels warmer than female in summer. The neutral temperatures of male and female were 26.3 ℃ and 26.7 ℃, respectively. The acceptable temperature ranges of them were 23.8 ℃~28.7 ℃ and 24.2 ℃~29.2 ℃, respectively. This study provides reference for the studies on thermal comfort and thermal adaptation of university dormitories.