A general Decision Support System (DSS) uses three major units to provide a user-friendly interface which assists managers in making decisions easier. This paper developed a Decision Support System based on Markov Decision Process (MDP) to compose a better strategy in order to maximize the expected average reward by choosing the appropriate action sets in corresponding states. According to the Markov Chain Theory, this system can keep track the actions of the chronic disease patients served by a chain drugstore and help the corporation grasp or influence consuming behavior to further motivate customer’s purchase. In the end, by inputting the data collected from an actual chain drugstore into the system to contrast the profits between the suggested and original strategies; thus the system can propose a superior action set.