To achieve the low carbon economy of the new power system, an optimal dispatching model of a source-load cooperative game with life cycle assessment (LCA) is proposed. First, considering flexible and dispatchable flexible load, this paper builds a cooperative operation framework of source-load dual side with CHP units, gas boilers, electricity to gas and other equipment. Then, the greenhouse gas emissions of different energy chains in the source-load dual-side are analyzed using the life-cycle evaluation method, and a carbon trading cost calculation model is established by combining with a carbon trading mechanism. Finally, based on cooperative game strategy, a source-load bilateral cooperative operation optimization model with the objective of minimizing the total cost of the source-load cooperative alliance is established. The improved Shapley value method is used to allocate the cooperative benefits to members. The analysis of the algorithm shows that the proposed model is conducive to reducing the total cost of system operation, reducing system carbon emissions, increasing the amount of renewable energy consumption, and effectively promoting the development of a low-carbon system economy.