The "last mile" in logistic is the terminal link of logistic service for users, and directly affects the efficiency, cost and service quality of logistic. This paper presents a solving method based on lifting cabinet for the "last mile" in logistic (this problem). Based on the concept of gradual service radius, and the relationship between service satisfaction and distance from the demand point to lifting cabinet, this paper proposes a mixed integer programming model for lifting cabinet's location problem. Moreover, this paper designs a heuristic Lagrange's relaxation algorithm by taking into full account of the various constraints factors to solve the model. Finally, illustrative examples further analyze the number of iterations, iteration times and other indicators, which show the correctness of the results in this paper and the good performance of the proposed method.