Abstract: The summer thermal environment of typical rural dwellings in the mountainous region of Guanzhong was measured to analyze the climatic adaptability to the mountainous climate of Guanzhong. Then,a series of numerical analyses were conducted to investigate the influence of building thermal design parameters on the indoor thermal environment and to obtain the optimal design parameters for modern dwelling buildings in the mountainous region of Guanzhong. The results showed that the thick raw earth walls of traditional residential building provide good thermal inertia and can effectively attenuate outdoor temperature fluctuations. The attic with open grill windows can introduce low temperature outdoor air and take away the heat stored in the attic during nighttime, for achieving the thermal insulation and cooling objectives. In addition,improving the thermal inertia of walls,adopting ventilated roofs, arranging sun-shading elements for south-facing windows and adopting night ventilation technology have significant effects on improving the indoor thermal environment in summer. The average and maximum indoor air temperature are reduced by 2.9 ℃ and 3.4 ℃ when the thermal inertia index of the external wall is 27.18, the projection factor of south-facing window shading is 0.5, the night ventilation time between 18 and 9 o’clock and the ventilated roof is used, respectively.