With the increasing global smog phenomenon and gradual improvement of environmental protection awareness, the quantitative calculation of gas emissions from thermal power units and the assessment of gas emissions have become the key planning tasks for grid dispatch monitoring and environmental protection departments. Based on the smart grid dispatch control system platform and the physical connection of thermal power units, boilers and chimneys, real-time data collection and historical data recovery are achieved through different communication specifications in this paper. Based on the historical data, environmental assessment statistics and electricity price assessment statistics on pollutant emissions are carried out. Then the results are sent to the environmental protection department. It is proved that this method can avoid the problem of untimely data acquisition and ensure the accuracy of the data source. In addition, the availability of assessment indicators can be effectively improved, and this method provides a reliable basis for environmental protection agencies to formulate measures. The emissions of thermal power units will be reduced, and power supply security and environmental effects can be improved.