Abstract:  This present paper deals with the main methematical achievements of Dai Xu,a fa- mous mathematician of the Qing Dynasty:Dai Shi Series Numbers,Dai Shi Iterative Method, Kai Ji Duo Wei Jiu-Cheng-Fang Method and the Relationship between Exponents and Loga- rithms etc.,which have been ignored by former research workers.The paper also puts forward different understandings from the past research at the following points:the Artificial Loga- rithm,the Formula for Changing Base,the Binomial Theorem and so on.

Key words:  , Dai Xu, mathematical achievements, the history of Chinese mathematics