In order to study the thermal environment of rural houses in mountainous areas of northern Guangxi, thermal environment parameters were conducted in summer and winter, taking the representative old and new houses as examples. The results as follows. The climate in the mountainous area of northern Guangxi is unique, and it's humid in summer and humid in winter in mountainous areas of Northern Guangxi. In the same season, there is no significant difference in indoor thermal environment between old and new houses. During the summer and winter testing, the old and new houses are in Level-III environment standards for most of the time. On the whole, the indoor thermal and humid environment of summer houses is better than that of winter houses. In view of the structural characteristics of the rural houses in mountainous areas of northern Guangxi, the regional climate characteristics should be fully taken into account when improving the indoor thermal environment of the rural houses. The measures of strengthening thermal performance of enclosure structure, natural ventilation, sun-shading and heat insulation and heat collection and storage should be combined. It can serve as useful references for the study of thermal environment of rural houses in mountainous areas.