OBJECTIVE： To provide reference for replenishing and perfecting essential medicine selection method in China. METHODS： According to the requirements of essential medicine selection， based on the actual situation， target function and restraint conditions for essential medicine selection could be determined by the knapsack theory and the essential medicine selection model could be built. The feasibility of established model was analyzed by an sample. RESULTS： The objective function of established model was Min∑CjXj， the minimum cost of all the selected essential medicines. Other constraints included covered range of disease， ADR， contraindications， attentions， dosage forms and specifications. Nine kinds of common oral hypoglycemic drugs were selected as candidate drugs， from which glipizide， gliclazide， metformin and repaglinide were chosen as the essential hypoglycemic medicines with the proposed model. CONCLUSIONS： Established essential medicine selection model based on knapsack theory is scientifical， objective and with strong practicality.