Abstract: The article introduces the definition and type of traditional auction (one-side auction),and the operation way and classification method of double auction as well.The article also points out that double auction can solve the information dissymmetry problem in the market,and thus problems like “collusion” and “malice biding ” etc.can be effectively  avoided in single auction.Meanwhile,under the condition of permitting both buyer and seller to change the offer at any time(continuous  condition),the article  establishes single product double auction model,congeneric product double auction model and different-typed product double auction model,and provides good theoretical model for the research of market behavior in double auction.

Key words: traditional auction, double auction, multi-item auction, model