In the early 1970' s, the paper "A Preliminary Study on Climatic Fluctuations During the Last 5, 000 Years in China" by Chinese geographer Co-Ching Chu (Zhu Kezhen) became a weapon for refuting the prevalent view of "world climatic anomaly" and the "new ice age". Nowadays it has even become a basis for some to question the theory of "man-made global warming". In order to find out the source of Co-Ching Chu's thought on climate change, this paper analyzes The Diaries of Co-Ching Chu, and finds that he was mainly influenced by the mainstream view at the conference on"climate change" hosted by UNESCO and WMO in Rome in 1961, as well as being inspired by H. H. Lamb in some key point. It also cannot be excluded that Co-Ching Chu's attitude to abrupt climate change was influenced by the ideology of the "Great Cultural Revolution".