Abstract: Information is the heart of the society and it is the efficient cornerstone of the market economy. The impact of information on price is ignored by the conventional economics, which was based on supply and demand. This article analyzes the reasons for pork fluctuation by using microscopic theory of market structure. The results show that, backyard households pay too much attention to the current market price and follow the subject behavior of the scale breeding ,which led to numerous farmers herd behavior and is the main reason that causes the imbalance of supply and demand of pork cycle. The reasons for the majority agricultural products price fluctuation are information scarcity and the herd behavior. Therefore, it should cultivate agricultural operators to collect and use the awareness of the market information, found the information databases of agricultural production, circulation and supply and demand, to provide information for farmers, decision-making and production.