The use of passive technology to improve the thermal environment of traditional rural houses has become an effective strategy. In this paper, we conducted a field investigation on the traditional wooden dwellings in southeast Chongqing, and found that the thermal environment of the three types of traditional dwellings in the shape of “One”, “L” and “U” were all poor. Combined with the climatic conditions, further simulation shows that the thermal stability of the envelope structure of the three types of residential buildings is poor and is easily affected by external temperature fluctuations. The “U” dwellings have the worst thermal stability, with the dining room and hall areas having the highest and lowest indoor temperatures, respectively. Therefore, taking the “U” shaped house as an example, this paper compares and analyzes the changes of indoor thermal environment before and after the passive design strategy, and the results show that the selection of a reasonable window-to-wall ratio and the passive technology suitable for the renovation measures of the outer envelope in this area can effectively improve the quality of the indoor thermal environment and reduce the fluctuation of temperature. This study further enriches the architectural types of the thermal environment of traditional rural houses in China, and provides a useful reference for the renovation of southeast Chongqing traditional houses.