The Semi-presidential system has been implemented for more than 20 years since 1997 Reform. However, there have been experts', pundits' and public's voices of reforming. Is it true that Semi-presidential system must be reformed for a series of problems? If the Semi-presidential system is replaced by another constitutional system, can it benefit our society and political situation? In the study, the questions will be discussed from perspectives of Law and real situation, and analyze the possibility of replacing existing Semi-presidential system.