Under the condition of market economy, the price of goods changes with internal rule and relation of supply and demand in the micro-market. Because of complexity of real economic system, the fact that supply is not all equal to demand every time needs use the disequilibirium analysis which nears well reality instead of traditional equilibirium analysis. In the state of disequilibirium market, according to the adjustment function for market and under synthesizing two basic adjustment equations of price, the stability of price for disequilibrium system has been studied based on the equations of supply and demand and using the adaptive expectation mode to forecast price .These conditions of stability of the system have also been given, which benefit to study structure and capability so as to search for dynamic law for the economic system .