Abstract: Based on the problems of emergency response grade and quick response for hazardous chemicals accidents, this paper provided a way which used concentration of benzene, exposure time of staff and diffused areas to measure off the emergency response grade by fault tree analysis. The emergency response was divided into initial stage and late stage during accidents. Taking Henan Shenma Nylon Chemical Co.,Ltd for example, emergency response grade by fault tree analysis was built to measure off the emergency response grade of leakage accident with benzene. Further more, the emergency response process of benzene leakage accident was analyzed.