Green transportation infrastructure construction is the key task of green low-carbon action in transportation, and the carbon emission intensity of tunnel project is much higher than the average value of carbon emission intensity of highway project. This paper uses the carbon emission factor method to carry out carbon emission accounting for the tunnel plan and Excavated Slope plan of a section of Xiongxin Expressway. The Excavated Slope plan can reduce carbon emission by 26,392t during the construction period, and the cut-and-slope scheme can reduce carbon emission by 18,882t during the operation period, and the cut-and-slope scheme can generate 15.64 million yuan of benefits by using the carbon trading data to convert the carbon reduction effect into economic benefits. In the original program selection, the tunnel plan and the Excavated Slope plan are not much different in terms of technical difficulty, but the construction cost is low, if we consider the benefits of energy use and carbon emissions, the Excavated Slope plan will have a clear advantage, and it can provide a more comprehensive idea for the route selection.