During a time when environmental issues are one of the biggest problems in the world, the development and growth of developing cities can no longer be discounted. As a typical developing city, the building energy consumption of Lhasa had a large scale increase with the living standard enhancement of people. Through the local measurements, the information as indoor air temperature, the evaluation of the thermal environment and so on was collected. The result shows the existed residential buildings used the direct gain system and the attached solar space system spontaneously. However, the indoor thermal environment still needs to be improved. Considered that Lhasa was classified into central heating area, it will face the problem of huge increasing of the heating energy. The basic models of direct solar gain system were established for studying the affecting rules of passive design elements. The last result gives suggestion for the local residential building design.