In this article,the study describesusing office-software Excel to program the computing system of gas spring sub-support of the automobile tailgate by establishing the mathematical model for the gas spring sub-support system of the automobile tailgate. First, using programed designing method to read the basic plan’s information of the support system which included in the 3D system. Then, finish the optimized structure calculation of the basic plan as the design required. Third, put the optimized plan into the 3D software and finally with the help of twice develop result, on click attachments for completing the support system’s detailed structure autodesign. The whole process is very quick and exact and scientific.