Starting with a broad conception of public sphere, this paper analyses the nature, dynamics and political functions of online Chinese cultural spaces, particularly newsgroups, online magazines and bulletin board systems. Although these spaces are located both in and outside of China, the global nature of the Internet gives them a transnational character. The dominant language of communication in these spaces is Chinese and the `publics' are drawn from what Tu Wei-ming calls `cultural China'. Analysis based on ethnographic data reveals the size and diversity of these spaces, as well as their similarities, differences and connections. Further analysis shows that these online spaces have had visible influences on trans-national politics and civil society in China. The picture that emerges from this analysis is that of a transnational Chinese cultural sphere. The article concludes with a discussion of three key conditions of its emergence: media, culture, and society.