Since Friedman published his article on auction theory in 1956, auction theory has made great progress. " Counterspeculation, auctions and sealed tenders" made by Vickrey in 1964 was the most famous article in this field. The Bench mode and Revenue Equivalence Theorem (RET) are the footstones of later discussion. The research structures have been formed and outcomes in this field are abundant through more than 50 years. Researchers are now going on to study new problems in this field. With the development of E commerce, Researchers devote themselves to the study of auction theory under the environment of E commerce which we call it online auction theory. We will first introduce the auction online and the research content and method of online auction theory. We will present the direction for the potential research in the last section of this paper and wish that we could give some to help the researchers who have a mind to study up on it.