Research purposes: It has been an unsolved difficult problem in engineering to conduct fabrication calculation for reinforcement structure when complex bar arranging is required on complex cross—section．The right solution has not been given to the fabrication on the non—symmetric and non—equably reinforcement section．Taking AutoCAD fits the secondary developing platform，based on ObjectARX and VC++ along with analytic method，iteration method and graphic method，this paper initially perfects fabrication calculation for reinforcement structure when arbitrary bar arranging is required on arbitrary cross—section(allowable stress method)，and as a result，a fitting arbitrary bar arranging program I’S made with allowable stress method．