This study applies Markov chain method on developing a decision support system, which first combines the historical records of professional baseball and sets up the transition matrix for each player based on the statistics, and then the transition matrix for nine batters in a given order determines the run distribution produced by this lineup. The results of this decision support system can be used to compare with the ball game records of Chinese Professional Baseball League and the historical data can be used to verify the accuracy of the estimation of this decision support system.