Multimodal plays a more significant role in long distances transportation of hazardous materials, while there haven't been systemic risk evaluation methods to hazmat multimodal transportation. Considering that the risk of hazmat transportation has the characteristics of low probability and high consequence, this paper studies how CVaR applied to the routing optimization of hazmat multimodal transportation while CVaR could better compute the tail loss of risk. We build a multimodal hazmat transportation risk assessment model in this paper, and prove its effectiveness by a computational study. Results show that the proposed model can provide a CVaR optimal transportation path to hazmat multimodal transportation in realistic.