According to the observations of such as Samuel P. Huntington, since the mid-1970s, we could find the so-called ”Third Wave of Democratization” almost everywhere in the world, including the countries of ”the Second World” (the Soviet bloc) and ”the Third World” (especially in East Asia and Latin America). Because so, not only many countries chose the democratic system, but the Democracy also seems to become the main ideology of the late 20th Century. Anyway, in this paper, we try further to realize what will happen between democratic movement and transition of constitutional system. Brazil and Mexico (all in Latin America) will be our focus and illustrations.