An optimization method using mixed integer non-linear programming ( MINLP) based on the multilevel refrigeration system superstructure was developed, with the lowest overall costs per year including operating cost and age depreciation of equipments as the optimal objective. 在多级制冷系统超结构的基础上,以年操作费用与设备年折旧费用之和的年度总费用最低为目标函数,建立了多机制冷系统优化的混合整数非线性规划。