The proliferation of smartphones exploits many new opportunities for mobile advertising. Many researchers believe that mobile advertising will be not only a killer application in mobile commerce, but also a noteworthy business model for many emerging mobile applications to monetize. Location based advertising (LBA) is a new advertising that integrates mobile advertising with location based services. Since LBA is related to the location of smartphone users, we analyze the moving trajectory of smartphone user and then try to find out the suitable endorsers for disseminate advertising. In this paper, a mobile social advertising mechanism, which considers the factors of preference, location of service, moving trajectories of smartphone users, and the influence power of endorser, is proposed to enhance location based commerce. When the targeted users for location based service is identified, the proposed mechanism can discover the most appropriate endorsers, which can disseminate the ads to the target users at a suitable location. According to the evaluation model, location based service providers know that how to choose the endorsers for disseminating advertising messages so as to attract the most smartphone users.