Abstract: This article aims at caving corner residual orebody by trench bottom structure in Xishimen Iron Mine. SURPAC software was used to calculate the ore volume,amount of metal and grade. A mathematical model of multi-objective optimization was established to maximize the amount of metal and grade. According to the special situation of corner residual orebody mining,the amount of metal was selected to be the main object. SURPAC software was developed to automatically calculate by using TCL script. With the help of the script software,all factors in the constraint were tested. The optimum position of trench bottom structure was obtained,which is on the 103.1 m level and 18.65 m to the orebody. Compared with the original design,the amount of metal is increased by 27.79% after this optimal design.