Czech Republic and Slovakia have similar historical backgrounds: they both had been ruled by Austro-Hungarian Empire, combined together to be Czechoslovakia after world war I, been ruled by Nazi Germany and USSR during and after world war II, and become newly post-Leninist democratic countries. In 1993, both Czech Republic and Slovakia adopt parliamentary system. However, Slovakia instituted popular presidential election in 1999, and so did Czech Republic in 2012. Until then, both countries are semi-presidential. The author tries to explain why these two countries changed their constitutional order from parliamentary system to semi-presidential system by the theories of constitutional choice. In the last part of this paper, the author will give some suggestions of constitutional reform to Taiwan according to the experiences of Czech Republic and Slovakia.