In southern area of china, the problem that balancing heating load in winter with cooling load in summer to ensure indoor thermal comfort when designing building envelop still remains. In this article, the correlation between thermal characteristics of building envelope and energy load is found by analyzing dynamic thermal process of buildings in hot summer and cold(warm)winter zones. In addition, the thermal characteristics of building envelope which affect indoor thermal environment and thermal stability of building are revealed. Also, the impact mechanism of enclosure thermal performance on indoor thermal environment and thermal stability is studied. By taking the balance between winter heat preservation and summer heat dissipation into consideration, the calculation of annual building energy consumption would be carried out, based on which the existing enclosure energy-saving method is evaluated from the standpoint of energy-saving effect, safety, reliability, economy and practicability. Finally, the climatic-suitable thermal design and its structure type of the enclosure is proposed.