The transportation industry is the second-largest source of greenhouse gas emissions after the power industry. In recent years, countries have paid more and more attention to their "low-carbon" development. How can the transportation industry assume the corresponding responsibility for low-carbon emission reduction, Green and low-carbon transportation has become a hot issue for industry development. Low-carbon multimodal operation is an environmentally friendly transportation mode. By integrating the technical and economic advantages of multiple transportation methods, it can effectively reduce the carbon emissions generated during transportation, and it has gradually attracted the attention of major transportation companies. Based on the dual constraints of cost and time, this paper incorporates carbon dioxide emissions into the multimodal transportation and converts the carbon dioxide emissions into the cost of carbon dioxide emissions through the carbon price function, forming the total cost of the entire transportation process. Under the time constraints, the article establishes a low-carbon multimodal transport optimization model, uses a genetic algorithm to solve the problem, and obtains the best low-carbon multimodal transport combination mode and route. The research explores how to establish a low-carbon combined transport mode under multiple constraints based on the enterprise level, and puts forward corresponding policy recommendations. The research conclusions have reference significance for promoting the low-carbon structural reform of the supply side of China's transportation industry.