This paper resents a preliminary Agent-based Model for modeling the interaction between knowledge sharing repository, such as forum or feedback system, and used-car market, and introduces knowledge recognizable quality k-quality as the linkage between tow sides. In knowledge sharing repository where seller agents use different strategies: altruistic sharing, sharing basic knowledge, and advertising, to creating articles would impress potential consumers, and leverage influence among participants to adjust profit margin. And buyers can read and learn available information from to increase their own knowledge and receive others influences. In this paper, we use proposed modeling to examine the seller's strategies about sharing price evaluation knowledge to customers, and look into the profit change while agents interact in both knowledge exchange market and used-cars market.