Abstract：The late Ming Dynasty and early Qing Dynasty was a crucial period of western learning. The Case of the Imperial Board of Astronomy during the Kangxi period was a milestone of western learning, and the first teaching plan which had a significant impact on the following ones. Yang Guangxian, a controversial person, initiated the above case. This paper explained why Yang Guangxian held such a radical view toward western culture and Catholicism from the following perspectives: his life experience and personality, the challenge of western sciences to Chinese traditional concepts, the conflicts between Chinese and Western culture, and his view of Catholicism's bad impacts on China.

Keyword：Yang Guangxian;western learning;conflicts;