Plan design of residential building is usually based on intuition,so there are often shortcomings in room orientation,natural lighting,ventilation and energy saving,causing some problems in its function.A concept of Predominance Score is suggested for different locations of the building according to the room orientation,natural lighting,ventilation and energy saving.Based on the low-density characteristics of isolated house,the suggested Predominance Score(PS) is assigned to each specific zone based on room orientation,amount of natural lighting sources and number of inner walls etc.Then,the plan design is carried out according to the order of PS.This strategy will help architects to make decision on technical analysis rather than on intuition.A case study shows the validation of the suggested strategy.