"Constitutional democracy" is the democratic system adopted in many countries today, and constitutionalism is also the foundation of democratic system. Constitutionalism is to regulate the operation of the power of the rulers and the protection of the rights of the ruled, and it is also the basis of representative democracy. Its role is to prevent the abuse of government power and to protect the libertiesand rights of citizens. Traditionally, constitution does not directly relate to whether the government is democratically elected, but modern constitutional theory is often associated with democratic concept tightly. Constitution embodies the spirit of constitutionalism, and is regulated in the Constitution. Recently, constitution is gradually combined with the concept of democracy. Constitutional democracy is a combination of constitutionalism, democratic values, and formed by the framework of a republic country; however the idea of concept of constitutional development can be realized practiceconcretely in the country of rule of law.