Climate comfort and its variability are of great importance to human comfort, health and well-being, as humans may suffer dire consequences when they are exposed to the environments with heat or cold stress. The climate comfort index represented the integrated effects of meteorological variables on the human thermal sensation. The annual and seasonal climate comfort index values were calculated based on the monthly data of the temperature, relative humidity, and wind speed from 591 stations in China between 1966 and 2016. Using the empirical orthogonal function analysis, the dominant modes of climate comfort index variations were extracted by the first two modes, which accounted for more than 50% of the total variance. The results showed that the annual and seasonal climate comfort index values displayed a latitudinal gradient, and increased towards the south except for the Qinghai-Tibet Plateau. The most frequently perceived thermal sensations were labeled as "cold", "comfortable", "cold" and "extremely cold" conditions from spring to winter, respectively. For annual and seasonal climate comfort index, the consistent increasing trend was detected in most regions of China in the first mode. The sensitive areas were mainly located in the central, eastern and southern China in winter, while in the northern and western China in summer. In the second mode, the fluctuations between upward and downward trends were observed. The sensitive areas were located in the central China in summer, in the southwestern and southern China in autumn, and in the northern China in winter. This study provides the important information for the improvement of human settlement comfort.