The stability of grain prices relates closely to the development of China’s economy, social stability and quality of Chinese people’s life. However, with the gradual openness of China’s grain market and series of newly-issued China’s grain policies, the volatility characteristics of China’s grain price may experience some structural changes and whether it becomes more stable still remains controversial. In this paper, we investigate the fluctuation characteristics of some main grain prices during the past two decades by using Structural Break Regime Switching Model and the Structural Break Model. We find that China’s grain price has become more stable since 2004 with narrowing low and high growth regimes. The implementation of Minimum Purchasing Price Policy and the semi-separation of domestic and international grain markets may explain part of the reasons for the stabilization.