Abstract: Fire and explosion accidents in oil depots are essentially originated by the existence, continuous production and untimely identification and control of hazard sources. To control all kinds of hazards related to oil depots effectively, the occurrence of fire and explosion accidents should be prevented from the source. Based on the related accident cases and the viewpoints of modern safety science, hazard sources of fire and explosion in oil depots were identified and analyzed based on the theories of three types of hazard sources, and the relationship among the three types of hazard sources and their accident cause mechanisms were investigated. The (Analytic Hierarchy Process, AHP) model of fire and explosion accidents in oil depots was developed. And finally, the importance and weight of the related factors were determined by means of analytic evaluation and integrated computation. It is shown that the existence of the third kind of hazard sources (organized hazard sources), such as organization errors, is the fundamental cause of the first (inherent hazard sources) and the second kind of hazard sources (triggered hazard sources), so the key to fire and explosion prevention in oil depots lies in controlling the third kind of hazard sources.