From the perspective of nationality, based on the 5th and the 6th population census of People's Republic of China, this paper analyses the spatial-temporal pattern of the cultural diversity in China with the construction of cultural diversity index, culture Geordie coefficient and nation primacy index. The results are as follows:①the level of the cultural diversity in China is characteristic of spatial difference. The spatial pattern is characterized by a lower level in mid-eastern China and a higher level in western borderland, a lower level in the urban area and a higher level in the rural area; ②the cultural diversity in China is changing slowly;③changes of the cultural diversity in China are pluralistic. Comparative researches between the calculation based respectively on the 5th and the 6th population census of People's Republic of China prove that there are 13 provinces whose cultural diversity decreases and 18 provinces increases. At the same time, changes of the cultural diversity respectively in the rural area and the urban area are distinctive;④the cultural diversity is paradoxical. While the level of the cultural element diversity in China is not high, that of the cultural spatial diversity is relatively high;⑤the cultural diversity in China and its spatial-temporal pattern are the integrated effects of such multiple factors as geographical environment, ethnic composition, human history and population flow. The overall level of cultural diversity is determined by the structure of pluralistic integration of Chinese nation; the complexity and diversity of the geographical environment lead to the basic spatial-temporal pattern of cultural diversity; the multi-component and thickness of the history promote the formation and evolution of the pattern of cultural diversity.