Abstract: The haze weather, which has appeared continuously and frequently in recent years, cause the profound reflection on the problems of environment and energy once again.And it has also sounded alarm to HVAC industry.In this paper, the author synthetically analyzes six aspects to optimize HVAC system design and equipment selection from the viewpoint of building indoor micro environment.In the end of this paper, the author puts forward the passive buildings with purified fresh air and better indoor air circulation, which are the most effective measure to prevent the haze weather.It can also be used to eventually establish standards and specifications for optimal design of HVAC system.