Abstract: The Taizhou Fm reservoir in Caoshe Oilfield of the North Jiangsu Basin is a complicated and small fault block reservoir,its oil recovery by water displacement is only 32%.Combinating the laboratory and simulation results on CO₂ miscible displacement and field experiment,the theorical and pratical analysis and contrast of oilfield development are accomplished.The oil recovery of this reservoir could be enhanced upto 47% according to results of laboratory experiment and numerical simulation,and higer 15% than water drive.From May 2005 to Dec.2009,the field experiment of CO₂ miscible displacement has been finished in Taizhou Fm reservoir of Caoshe Oilfield,the cumulative amount of CO₂ gas flooding is upto 5 842×10⁴m³,the production of crude oil is increased 3×10⁴t,the oil recovery is enhanced 2%.CO₂ miscible displacement is an effective method of enhancing oil recovery,which has important reference value on tertiary oil recovery in complicated and fault block reservoirs.