The objective of research is to develop a decision support system that can accommodate evaluation models to optimize multimodal transportation routes between Thailand and Vietnam for Logistics service providers: small and medium enterprises. This research is for transporting services, originated from Bangkok in Thailand to destinations in Hanoi, Danang and Ho Chi Minh City in Vietnam within the qualitative criteria (risks of transportation) and quantitative criteria (budgets and time). The risks of routes are divided into 3 groups; risks of freight, risks of infrastructure and equipment of transport routes and risks of illegality. The decision support system consists of a multimodal transport cost-model which is used to find costs and time of each route as the database for making decision and the Zero-One Goal Programming (ZOGP) which is used to calculate the optimal amount of transportation routing costs, routing time and risks of route: under budget, time and risk criteria from the user.The user can define the significance of 5 criteria as user’s desires. From the study, the high potential routing is the route from Bangkok to Ho Chi Minh City, it consists of 9 multimodal transportation routes. Then the calculation, the optimal multimodal transportation route is the one that a truck carries goods from a customer’s factory to Lam Chabang Port and they (goods) are transported to Ho Chi Minh City port then are carried to a customer’s site by truck. The route between Bangkok to Hanoi, consists of 21 multimodal transportation routes. The optimal route is the one used by carrying from a customer’s factory to Lam Chabang port by truck and moving to Hai Phong port then carrying goods by truck to a customer. The route from Bangkok to Da nang, consists of 11 multimodal transportation routes. The optimal multimodal transportation route is the one of which goods are carried from a customer’s factory to Lam Chabang port by truck and they (goods) are moved to Da nang port then carried by truck to a customer.