This paper applied signaling concept to analyze the economic meaning of existing-housing contractwarranties. In order to decrease the problem of asymmetric information, brokerage firm can offer the methodof warranties to inform the buyers the quality of product or service. The buyer may believe that brokeragefirm cannot impossibly offer the warranties to the defects in product(outcomes of effort ), so he would believecertainly the quality ofproduct(service) to be better. This is credible in a long run, so called signaling. Perhaps, the existing-housing contract warranties existed the function of the signaling to transmit information toconsumers. The existing-housing contract warranties can't guarantee no problems to the transaction process, but itmay inform to the consumers" that brokerage firm offering the warranties will possibly reduce the problemsin the transaction process." Applying the signaling theory, we can get lots of conclusions. In separating equilibrium, if brokeragefirm is lower to the cost of warranties, then he will offer the warranties. If brokerage Firm is higher to the costof warranties, then he will not do. In pooling equilibrium, the brokerage firms , any types or costs of warranties, all transmit the same signal and attain the same commissions, then this signal must be no any warranties.