The characteristics of new power system user-side ubiquitous resources that are scattered in distribution, large in number, small in capacity and stochastic in nature create difficulties for user-side fine-grained carbon emission calculations. In order to accurately measure and assess the level of user carbon emissions in the power system, the sources of the power flows in each node of the power system is first analyzed through the power flow tracking method to determine the indirect carbon emission responsibility of each node. Then, the distribution of carbon flows in the power system is obtained by combining the carbon intensity of different sources according to the principle of proportional sharing. Finally, through the proposed load-side indicators of various electric power emissions, the cleanliness of different nodes is assessed so as to guide the users to use cleaner energies more often in order to reduce their own carbon emissions. And the real power system data are used for example validation to verify the rationality and usability of the proposed method.