The neogenic soil body is of great significance in the study of regional environmental evolution, nutrition element release and secondary ore formation. Using such means as chemical analysis, X-ray diffraction pattern, polarizing microscopy and scanning electronic microscopy, this paper has discussed the features and formation processes of secondary calcites in calcium nodules within ustic vertisols in Yuanmou Basin, Yunnan Province. Secondary calcites dominate calcium nodules, and the crystallinity of calcites is high. Calcium nodules and secondary calcites are closely related to climate and micromorphology. The features and formation of calcites reveal that dry and hot climate has prevailed in Yuanmou Basin since Holocene.