Abstract: The paper aims to improve the evaluation mechanism of comfort degree of human settlements in summer. Based on the daily meteorological data from 1957 to 2016 and the hourly meteorological data from 2005 to 2016 in Ningbo, the authors analyzed the variation characteristics of comfort degree in summer and its responses to the temperature factors, and developed the evaluation model of daily comfort degree in summer on the basis of comfortable level. The results showed that: the interannual variation of comfortable days in summer during 1957-2016 was not obvious in Ningbo, but the trend of the start date of summer uncomfortable day being advanced was obvious; the diurnal variation of comfort degree index which was the highest at 13:00 was similar with the diurnal variation of air temperature; the comfortable and uncomfortable days in summer were significantly correlated with several factors: average temperature, average minimum temperature, average maximum temperature, extreme maximum temperature and high temperature days. The authors carried out the historical back-generation simulation and the consistency test for the new evaluation model of comfort degree, and found the results of comfortable and uncomfortable levels were higher, and in 2016, the consistency rate of each level was more than 91.7%, which indicated that the new model had good evaluation effect, and could meet the demands of business service.