The implementation of energy conservation and emission reduction is significant for China's iron and steel sector. Currently, the carbon emission responsibility accounting method cannot reasonably classify steel enterprises' responsibility and does not effectively promote cooperative emission reduction between steel enterprises and the consumption side. The baseline value of the carbon emission responsibility accounting method is used for the cooperative emission reduction model of steel enterprises and the consumption side in this study. The carbon quota allocation among steel enterprises before and after cooperative emission reduction, as well as the one for cooperative emission reduction between enterprises and the consumption side, are optimized using the Shapley model of the cooperative game of benefit distribution. The research results show that: (1) the carbon emission responsibility obtained by enterprises that do not purchase outside coke is lower and that this is contrary to the goal of reducing carbon emissions, as it does not reduce the total amount of carbon emissions produced by enterprises and consumers. (2) The transfer of carbon emission responsibility from steel enterprises with high responsibility to those with low responsibility would result in cooperative emission reduction among steel enterprises, which could reduce the activeness and competitiveness of enterprises with low carbon emission responsibility. (3) The increased low carbon level λ of crude steel will minimize the overall amount of carbon emission responsibility shared by enterprises and the consumption side. Therefore, the mutual transfer of carbon emission responsibility between enterprises has less impact on the cooperation between enterprises and the consumption side to reduce emissions. However, the benefit of carbon emission responsibility will increase as both parties sell to the outside market.