Abstract: In order to determine the influencing factors and mechanism of carbon dioxide corrosion in Jiangsu Oilfield and find a solution for casing corrosion,we independently developed dynamic corrosion experiment device,and carried out downhole dynamic corrosion experiments 1/4 arc steel sheet of Φ139.7 mm×Φ124.3 mm×16 was used to simulate carbon dioxide corrosion on casing at partial pressure of 0-2.5 MPa,temperature of 60-80 ℃,flow rate of 0.02-0.04 m/s,to evaluate the corrosion rate and corrosion morphology and analyze the micro-morphology of the corrosion products.Based on the experiment,casing corrosion mechanism was studied.Experimental results show that API N80 casing steel exhibits higher corrosion rate.The average corrosion rate is 0.168 9-0.571 8 mm/a,and would increases with the increase of the partial pressure of CO2,temperature and flow rate,resulting in serious carbon dioxide local corrosion morphology.The microstructure analysis shows that flow velocity is the main effect factor which causes corrosion of oil pump suction port near the casing,and its corrosion rate is 0.571 8 mm/a,which is consistent with the corrosion casing leakage situation on site.The research results show that the new experimental device can simulate the carbon dioxide corrosion accurately,providing a new test method for related experimental study on casing corrosion mechanism.