Abstract: Pig farming industry has an important position in China. The frequent fluctuation of pig price in recent years has certain impact on smooth running of national economy and healthy development of pig farming industry. Known from studying the relevant literatures, there were both endogenous and exogenous factors in fluctuation of pig price, and then the paper proposed to study the causes of fluctuation of pig price using theories of economics. Cobweb model is a principal tool to explain price fluctuation of agricultural products. By analyzing data from January, 2000 to July, 2012, it is found that the fluctuation of pig price in China presents a state of “cobweb disturbance” showing divergent case in general while convergent case and closed case in certain periods of time. It is believed that this phenomenon was closely related to change of macroeconomic environment in China, particularly the change of monetary policy represented by the interest rate. By analyzing pig farmer’s behavior to price change of piglet and feed, and analyzing relation between real wage and pig farming industry from the angle of macro labor demand and goods supply, the paper brought up two new exploratory explanations which were helpful to supplement the deficiency of cobweb model.