With China's sustained and rapid economic development, the demand for hazardous chemicals is increasing. Due to the special nature of hazardous chemicals, the occurrence of an accident may lead to a more destructive result than the general transport accidents, so the transportation of hazardous materials needs special attention. Based on this background, this article analyses the risk of hazardous chemicals transportation through risk assessment model. First of all, this paper considers all kinds of cost in the transportation of hazardous chemicals, then classifies the transportation risk into different kinds, and by the ways of certain function forms this into cost, which will make hazardous chemicals transport cost and risk cost in the same objective function. This model can be used for the government to formulate policies to reduce the risk and help the enterprise choose a reasonable path lower the cost. This article considers more factors in the risk assessment model, thereby increasing the accuracy and practical significance.