OBJECTIVE：To provide reference for the improvement of centralized drug procurement system in China. METHODS：Based on gaming theory ， it was assumed that all drug manufacturers participating in the bidding were rational ，and their goals were to maximize their own interests. Drug manufacturers participating in the bidding did not know the quotations of other drug manufacturers participating in the bidding before the bid opening. There was no collusion among drug manufacturers participating in the bidding ，and the quotations of each manufacturer were repeated as small probability events ，which meant it was basically impossible to occur. Under the above assumptions ，a static game model with incomplete information was constructed for the bidding process to analyze the influential factors of price reduction of drug quantity purchasing ，then related suggestions were put forward. RESULTS & CONCLUSIONS ：The gaming model was established successfully. The model covered the number of enterprises with the qualification to participate in the centralized procurement of drugs ，the number of the most successful enterprises and their declared price ，cost，quotation strategy ，the average agreed purchase volume after bidding ，the probability of winning the bidding ，the expected income after winning the bidding ，etc. The larger number of unsuccessful manufacturers ，the lower upper and lower limits （but the lower limits could not lower than cost price ）of drug price ，and the greater agreed purchase quantity were all beneficial to acquire a lower selected price under this model. Based on this ，the author suggests that the government should actively construct the competitive pattern of N＞n（the number of enterprises applying for qualification is greater than the number of enterprises that can be selected at most ），set a reasonable price upper and lower limit and specify the purchase quantity when improving the centralized bidding system of drugs in China.