Aiming to address the high fuel consumption problem of the main engines of tugboats operating in ports, this study proposed a fuel-saving optimization method that is based on an improved beetle antennae search. On the basis of the analysis of the energy transfer mechanism of ships, machines, and slurry, a mathematical model of fuel consumption of the main engine of a tugboat was established. The speed of each route was then optimized using the developed model. As an intelligent single-search optimization algorithm, beetle antennae search entails low computational complexity and is capable of optimizing complex models. The improved chaotic beetle antennae search can solve the slow convergence of the traditional beetle search. Through an example analysis, the effectiveness of the proposed method was verified and compared with that of beetle antennae search and genetic algorithm. Results proved that the improved beetle antennae search achieves the best optimization effect, which proves the effectiveness of the method.