Emergencies are sudden, urgency, uncertain and uncontrollable. In the course of expressway operation, accidents such as vehicle collisions and fires often occur. These accidents may not only have serious consequences, but may also cause secondary accidents. The consequences are expanded to reduce the efficiency of expressway traffic. In order to reduce the risk of expressway operation, it is necessary to evaluate the unexpected events that may occur during the expressway operation process, and analyze the demand of emergency resource on this basis. First, based on the uncertain inferences including evidence inference and case inference, a case library containing the characteristics of emergencies and the required emergency resource is constructed. The case library covers emergencies that have occurred and have not yet occurred but may occur. Secondly, based on the fuzzy evidence inference, the risk assessment of emergencies is carried out, and the fuzzy matching of the incidents is based on case fuzzy reasoning and the reasoning results are obtained, and then the types and quantities of emergency resource needed for the emergencies can be obtained. Finally, according to different types of typical cases in the case library, the analysis of different kinds of expressway emergency resource demand is carried out, and emergency resource reserve plan is carried out according to the most unfavorable situation to reduce the risk of expressway operation. The case verification is carried out through a expressway in Guangdong Province. The results show that the emergency risk assessment method can accurately evaluate the consequences, and can obtain acceptable reasoning results through case matching. Through typical case analysis, the emergency resource reserve plan can meet the emergency response needs of the expressway operation process.