Abstract: This study focus on grian supply and demand balance of Yangtze River Delta. The research reflects the development series in time of grain production and consumption based on historic data, and forecasts the supplies and demands of grain on Yangtze River Delta in 2021—2030 by using ARMA model; and then constructing a framework of security mechanism of supply-demand balance from five perspectives such as safety of grain production, distribution, coordination of production and marketing, regional emergency, and effective regulation. Aiming at security mechanism, the article put forward the safeguard measures from ideas, technological innovation, talents, fiscal and financial, collaboration and cooperation.