Study on the loss of social welfare caused by search in the market based on the asymmetric information

According to the traditional economics, the best efficiency of resources allocation is produced in perfectly competitive market. However, the conclusion neglects the dealers\´ “search” which is to get the complete information. This is a process which costs so much time that it has a big effect on the market equilibrium. As a result, the cost of search largely affects the efficiency of resources allocation. The study is based on the Asymmetric Information theory and the Search theory, it discusses the destruction to perfectly competitive market and the loss of social welfare caused by "search", and puts forward the solutions-advertisement and setting up the third agency at last.