Abstract: Regional food security is the basis of national general food security. In this paper, risk factors of food supply and demand in China were qualitatively identified by using fault tree method, and after that the identification indexes system of risk factors of food security was established. Based on the qualitative identification, was risk coefficient method to quantitatively identify risk factors of regional food security was. Meanwhile, a case study was carried out in Dongting Lake area in Hunan Province, and the risk factors were classified according to their different risk sources. The results showed that: natural disasters, farmland resource constraints, water constraints, labor shortage, input cost constraints of fertilizers and pesticides, food consumption changes per capita, income changes, population change were the risk factors of food security in Dongting Lake area. The result can provide strong and relevant evidence for regional policy makers. Based on the results, risk assessment for food security also can be carried out.