In the context of carbon dioxide emission and carbon neutrality， as traditional power systems undergo transformation and upgrading towards new power systems， that has driven the explosive growth of a new generation of active energy agent （AEA） in distribution network， such as “photovoltaics， energy storage， virtual power plants， flexible loads， and electric vehicles”. However， the current electricity spot market is difficult to adapt to the differentiated physical and economic characteristics and diverse trading needs of various AEAs， and it is also challenging to clarify the additional environmental value of transactions. Against this backdrop， to quantify the contribution of AEA power generation and consumption mode to carbon emission reduction， firstly， a reputation evaluation model based on contract completion rate is proposed， with the AEA reputation value and transaction security verification results， the transaction sequence and transaction price are adjusted and updated. Then， allocation mechanism of environmental rights is designed based on regional dynamic carbon emission factors with power flow carbon label and morphological similarity index of user load-new energy resource （UL-NER） curves. Finally， to maximize social welfare， an energy block matching and clearing model is built， and the Gurobi optimization solver is utilized to solve the model. The results of case analysis and scheme comparison show that， trading mechanism not only increases AEA’s revenue and social benefits， but also enhances its ability to reduce carbon emissions.