Abstract: Relative merits of traditional comprehensive safety evaluation methods for oil tankfarms are analyzed. In order to overcome the drawbacks existed when traditional evaluation methods do not fully consider the fuzzy and unknown characteristics of information, evidence theory method is introduced into the field of oil tankfarms' comprehensive safety evaluation and an evidence theory-based model for oil tankfarm comprehensive safety evaluation is put forward. The model analyses the uncertain problems reflected on subjectivity in expert ' s opinion by basic probability assignment and its fusion, and then makes a comprehensive research on the fuzzy and unknown information in oil tankfarm systems. A comparison is made between the model and traditional model of fuzzy comprehensive evaluation with an example, and the result indicates that the evidence theory-based model is of usability and advantage for oil tankfarms' comprehensive safety evaluation.