The pay thickness is small and the production effect of steam stimulation is poor for Chen373 block in Shengli oilfield. Effect of CO2 and chemical agent on crude oil is analyzed by experimentation. At the same time, the production of compound stimulation of CO2-Chemical after steam stimulation was studied by reservoir simulation soft CMG. The result indicated that CO2 and chemical had good effect on the heavy oil. The viscosity reduction rate is 98.97% by CO2 and chemical synergy under the reservoir condition. The viscosity is 18.4% of that in the role of chemical agent. Compound stimulation of CO2-Chemical can complement formation energy and increase scope of crude oil viscosity reduction and production effect. CO2-chemical compound stimulation after six cycles steam stimulation contributes more production. Average cycle oil production of CO2-chemical compound stimulation is 480.5 t, which is 252.4 t more than steam stimulation. The return on invested is 1.64. The research provides evidence for producing transformation after steam stimulation for Chen373.