In order to improve energy saving efficiency of Harbin residential building, we select optimizing southern windows’ size to improve sunshade efficiency as research purpose, appropriate glazing floor area ratio of should be confirmed within the specification limitation according to Harbin’s climate. By controlling the southern windows’ area, height and width, wall thickness and visor width, energy saving efficiency can be improved by preventing direct solar insolation in summer, which can reduce the cost of room temperature refrigeration, without reducing solar insolation in winter. The energy-saving efficiency will be maximized by software simulation analysis, and the southern window normative design patterns is formed. Through calculating receiving heat of ground energy saving effect of the optimized southern window can be verified.