Abstract: Evaluating grain security state quantitatively and determining the index weight objectively are important for regional grain security. Considering the factors about grain supply and demand, an index system of grain security pre-warning was established, and a regional grain security pre-warning model based on entropy weight and extensional theory was built. The model was applied to the grain security pre-warning analysis of Anhui province in recent 11 years (2000－2010). The results showed that the grain security situation could be divided into three states: heavy warning (2000－2004), moderate warning (2000－2004) and security state (2007－2010). The change of grain security degree of pre-warning was consistent with the fluctuation of single pre-warning index, and comprehensive security degree gradually increased. The model proposed improves the capacity of grain security pre-warning, quantitative evaluating grain security state and gives a new way for implementing grain security supervision.