To better guide decision-making and cost optimization for LNG (Liquefied Natural Gas) tank container multimodal transport routes, aimed at minimizing transportation costs, a mathematical model for optimizing LNG tank container multimodal transport routes based on transshipment terminals was constructed. The study investigated a three-tier multimodal transport network consisting of LNG receiving terminals, transshipment terminals, and customers. A two-stage approach was employed in this paper. The overall transportation route planning problem based on transshipment terminals was addressed in the first stage, while the optimization of multimodal transport modes was dealt with in the second stage, building upon the results of the first stage. The GAMS, CPLEX, and DICOPT solvers were used for instance analysis of models. The results revealed that, compared to the traditional point-to-point direct transportation mode, the combination of transshipment terminals and multimodal transport could significantly reduce transportation costs. Meanwhile, sensitivity analysis on the capacity and discount coefficient of cross docks was conducted in this paper, and it was found that changes in the discount coefficient and capacity would have a direct impact on the selection of transportation modes, transportation routes, and overall transportation costs. The case studies validated the effectiveness and feasibility of the transportation model proposed in this paper. The research showed that adopting the transportation mode proposed in this article was expected to significantly reduce transportation costs and provide valuable reference for LNG supply enterprises.