This study compares roles and functions of staff supporting systems (Organic Laws and Statutes Bureau, Budget Center, and Library of Congress) in the legislative process among Taiwan, United States and Japan. According to the opinions from the 24 interviewees, we find out the following results: 1. Legislative assistance is the most important function of Organic Laws and Statutes Bureau and Budget Center. 2. Due to the insufficiency of professionals and the information asymmetry between executive and legislative branches, functions of the Organic Laws and Statutes Bureau and Budget Center still need to be improved, except the Library of Congress. Lack of space and equipment is the main problem of Library of Congress. 3. Roles of staff supporting systems should play as follows: professionals or experts, legislative assistance as a think tank, and unbiased viewpoints. 4. Future developments of staff supporting systems are: reorganization and increasing the professional staffs and strengthening the interactions among government, private sector, and the academic communities. 5. Research papers from the Organic Laws and Statutes Bureau and Budget Center are helpful to legislators. 6. There are two reasons why legislators have no demand on professional staff: First, the influence of reelection, including the precinct service, electoral system, political party, faction, election atmosphere and the performance of legislation. Second, present deliberation system of Legislative Yuan, including the problems of agenda-setting and legislative efficiency, incapability of establishing professional deliberation system, and the influence of party caucus negotiation exceeding the committee's professional deliberation. This study provides the following suggestions for staff supporting systems: 1. Increasing the budgetary personnel. 2. Strengthening interactions between staff supporting systems and the academic communities. 3. Clarifying the status of Organic Laws and Statute Bureau. 4. Providing valuable information and advice for legislators automatically and in time. 5. Transforming the National Library into Library of Congress. 6. Establishing professional deliberation system. 7. Improving the party caucus negotiation system.