On the Ideal Politeia, a number of philosophers, among them are Plato and Aristotle of ancient Greece, More, Bacon and Rousseau of modern Europe, have offered their own proposals. This paper argues that Rousseau, on one hand inherited the classical idealpoliteia teaching, which was set up by Plato and Aristotle, and fought against the intellectuals who advocate enlightenment; on the other hand stealthily betrayed these two Greek tutors and designed a new ideal politeia for Europe of the enlightenment age. The author of this paper believes that the deviation from the ancient Greek tradition was originated by Mores Utopian and Bacons New Atlantis in 16th century, and was accomplished by Rousseau. Therefore, the studies, both in what Rousseau deferred and what he inherited from the ancient tradition of ideal politeia theory and in his complicate and vague attitudes towards the enlightenment, can serve as the best way both to examine the enlightenment movement in 18th century and to start a serious consideration on the important question in western intellectual history whether the ideal politeia is possible or not.