A large number of papers and books on cosmopolitanism have been published since 1990, marking a renewed interest in the field among Western scholars. When we try to locate the original source of cosmopolitan ideas in human civilization, we find Chrysippus’ thought in western philosophy, and Confucius’ as its eastern counterpart. In this paper, I offer a comparative analysis of Confucius’ and Chrysippus’ cosmopolitan theories from the following three perspectives. I begin with the theoretical origins of the two thinkers on cosmopolitanism, which mainly center on the relationship between human beings and nature in their respective natural philosophies, and on the question of how to be a good person from their moral philosophies. Then, I explain the concrete schemes they posit for a cosmopolitan society. Finally, I compare their differing concerns regarding one’s attitude to family members or fellow citizens, which constitutes the main source of disagreement between them. In conclusion, I propose that both of their ideas can be located within a continuum of “moral cosmopolitanism.” The difference being that Confucius holds to a moderate cosmopolitan idea, while Chrysippus prefers a stricter version of cosmopolitanism.