Whether chemical flooding projects can gain large-scale benefits at low oil prices is under heated discussion.For this reason，post-project evaluation has been carried out for some implemented projects，and the key to reasonable evaluation results is the cost value. According to the cost level in the starting year of evaluation，the relationship between cost elements and development indicators is established to recalculate the historical cost of the projects. Then，in light of the development law，future cost is predicted to reconstruct the life cycle cost of the projects. On this basis，a post-project evaluation method for chemical flooding projects is proposed for some chemical flooding projects that have been implemented. Results show that chemical flooding projects can get very good economic benefits at low oil prices，and the cost per ton of oil is 10%-20% lower than that of water flooding units with the same water cut. In addition，when the oil price is 40 $/bbl，the economic limit on oil increment per ton of polymer for chemical flooding projects is about 15 t/t. The chemical flooding resources that meet this requirement in Shengli Oilfield have great potential，and chemical flooding at low oil prices still has great prospects of promotion. Further analysis indicates that the fluctuation in oil prices has little impact on the benefits of chemical flooding projects，and their benefits can be significantly improved by optimizing the dosage of reagents and extending their peak periods of working.