In the context of carbon cap-and-trade the outsourced emission reduction with energy cost trusteeship cooperation model was proposed for the single emission reduction mode of enterprises and the two emission reduction modes were compared and analyzed. The Stackelberg game model of autonomous emission reduction and outsourced emission reduction was constructed to compare and analyze the effects of cross-price elasticity carbon trading price and emission reduction investment coefficient on corporate profits and carbon emission reduction under the two emission reduction methods. The factors affecting the choice of emission reduction methods were further elaborated. The effectiveness of the model was verified by simulation. The results show that no matter what kind of emission reduction method the carbon emission reduction and profit of enterprises have a positive relationship with the cross-price elasticity coefficient. The increase of carbon trading price will mobilize the enthusiasm of manufacturers to reduce emissions and the carbon emission reduction of products will increase which will have a negative effect on profits. The increase in emission reduction investment coefficient has a negative hindering effect on the emission reduction of enterprises. The independent emission reduction investment coefficient ratio between the energy-saving service company and the manufacturer affects the choice of emission reduction mode of the supply chain. When the emission reduction investment coefficient ratio is less than the threshold the enterprise should choose the outsourcing emission reduction mode of energy cost custody cooperation and the change of decision-making factors will affect the timing of its choice of emission reduction mode.