Abstract: To reduce the total risk and cost related to the mixed storage and transportation of hazardous waste, a multi-objective optimization model under uncertain demand is proposed, which aims to jointly optimize decisions on facility locations, inventory control and route planning. Considering the risk derived from mixed storage of multiple types of hazardous waste, an environmental impact disutility function of treatment stations is formulated by introducing a toxicity coefficient and an odor factor. The resident disutility effect of transfer stations is considered to develop a corresponding risk assessment model. To cope with the uncertain demand of hazardous waste in storage and transportation, a computation method of total generation amount is modeled according to probability distribution functions, and the maximum storage capacity of facilities is estimated. A location and transportation model for hazardous waste of mixed storage and transportation is developed with the objective of minimizing total risk and cost. Given the complexity and multi-objective nature of the proposed model, an improved NSGA-II algorithm is designed to solve the problem. Finally, several tests are provided to demonstrate the effectiveness of the proposed model and algorithm. Computational results show that, multiple effective location-routing plans can be provided by the proposed method. Comparing to traditional risk models, the integrated assessment model can generate solutions with better trade-offs between cost and risk, achieving both personnel safety and environmental protection. Comparing to general multi-objective optimization methods, the improved algorithm can reduce the computation time by 38.79%, and solve problems of various scales within 1700 seconds while maintaining high computational stability.