We study a typical supply chain in which the supplier would like to offer trade credit to the budgetconstrained retailers．There exist two types of retailers (Type H and Type L) in the market．We define three different competition market，the high competition，middle competition and low competition market，according to retailers’preserve profits．Then，we set up an adverse selection model to inspect the designing of trade credits to the retailers in each competition market．Furthermore，we examine how the competition in the market affects the trade credit’s parameters and the supply chain’s performances，and the results show that the trade credit contract is able to coordinate the supply chain in the middle competition market．