Passive solar school dormitory is a suitable solar energy utilization mode in plateau because of maintenance-free, easy to operate, economical and energy-saving. For such buildings, the indoor thermal comfort range or rather acceptable temperature range is different from that in plain areas. Few studies on the thermal performance of such buildings have been found in the literature. For primary school dormitories, the indoor temperature during night contributes most for thermal comfort of the pupils living in them. Their ages are between 7 to 12 years old. This study was conducted in four primary schools in the Western Sichuan Plateau in China. The building basic information was collected. The indoor and outdoor meteorological parameters were measured. The pupils’ thermal sensation was investigated by questionnaires. It’s found that: (1) The wall of the Western Sichuan Plateau are mainly made of 200-370mm concrete blocks with an overall heat transfer coefficient of 2.5 to 3.4 W/m²K, and the overall heat transfer coefficient of single glass window is 5.5 W/m²K; (2) The thermal insulation performance of the building envelope is extremely poor; (3)During the test, the indoor air temperature during night varied from 1.1 to 7.6℃ while the outdoor air temperature varied from -7.4 to 4.8℃. In the coldest period of the winter, about two-thirds of the rooms have experienced indoor freezing, and about half of the students have experienced frostbite in winter. The relationship between thermal sensation and indoor air temperature was found and the thermal expected temperature was estimated to be 12°C. Pupils are accustomed to wearing thick clothes whose average thermal resistance is about 1.58 clo. The research results are helpful for the design of passive school dormitories in severe cold plateau.