In recent years, many large-scale oil depots have been built in the opencast coal mine in China. In order to prevent and control major accidents of the opencast mine, it is important to assess the risk of large-scale oil depots. This paper aims to bring about a quantitative risk assessment (QRA) method to assess the fire risk of opencast coal mines. Firstly, risk analysis of large-scale oil depots for coal mine are made, the hazardous characters of gasoline and diesel are described, and the risk consequences are discussed. It is found that pool fire is the most typical and serious consequence, therefore, a mathematical model of pool fire is introduced. Furthermore, the quantitative risk assessment (QRA) method is developed to assess the fire risk of the large-scale oil depots. The QRA method is applied to assess the risk of a selected large-scale oil depot in a large opencast coal mine in China based on the QRA software CASSTQRA. For the gasoline tank of 1 x 104 m(3), the death, serious injury, and light injury affected radius of a pool fire are 64.75 m, 75.66 m, and 106.86 m and the individual risk was acceptable. Finally, some suggestions are proposed to improve the safety of the large-scale oil depots. The study is useful for the safety management and prevention of major accidents in opencast coal mines.