The study examines the institutional factors which influence decision-making process of budgetary policy of the government in Tai wan. The multiple regression analysis which explains the fators influence the budgetary sizes tries to test the assumptions of rational-choice. The study uses the survey data to explore the characteristics of top-down budgetary processes, and observe the factors which influence the outcomes of budgetary policies, such as information distribution, constraints, communication, and decision-making process.