Abstract: The hierarchy gray assessment method is used to build a fire hazard assessment index structure system for oil tankfarm so as to carry out an overall assessment on fire hazards of oil tankfarm. This method is then integrated with the analytic hierarchy process and gray evaluation model. The authors analyze the factors affecting anti-fire and anti-explosion of oil tankfarm. A three-level fire hazard assessment hierarchical structure system for oil tankfarm is built, the AHP is used to determine weight set of assessment index and the gray assessment model is used for processing scoring results of the expert group to get the evaluation matrix so as to obtain tankfarm's fire hazard assessment results.Instance of the application results is in line with the actual situation of oil tankfarm, which indicates that the method is characterized by the scientific, simple and practical and can accurately reflect fire safety state oil tankfarm.