As the main disciple of Confucius,Zeng Zi inherited and developed the thought of Confucius in many aspects.Aca-danic circles have a lot of discussion in filial piety and cer~rlony,but few study the sincerity thought of Zeng Zi.The thought of sincerity development process fi'om Xin to Cheng and Cheng Xin.Zeng Zi inherited Confucius and influenced Zi Si and Mencius. The sincerity thought have important significace in Confucian.Lots of speech and action were recorded in Si-shu.This paper is based on Si-shu and some oth...