Research conclusions：The analytic result shows that energy consumption directly determines the carbon emissions,therefore by introducing the correlation coefficient energy consumption can be convened into carbon emissions.Because a lot of clean energy is used in the railway operation,and in the strict sense,the power itself does not directly generate carbon emissions,the energy consumption of railway is not entirely equivalent to carbon emissions,that need to be clearly stated in the carbon emissions calculation.Technology assessment and management evaluation are the main factors of evaluation system,and by using the AHP and expert scoring method,the weights of all levels can be determined.The method to calculate the carbon emissions and the system of evaluation on low-carbon effect presented in this article can be applied in such fields including emissions statistics,monitoring and evaluation in the railway sector.