Abstract: In view of the actual situations such as strong water sensitivity and poor water injection effect of the Lower Jurassic Hinggan reservoir in Sudert oil field, the Block B14 was selected for miscible CO2 flooding test in 2011. The obtained minimum miscible pressure of crude oil and CO2 is 16.6 MPa from slim tube test in laboratory, 1.0 MPa lower than the original formation pressure, which indicates that miscible CO2 flooding could be realized. The field test result shows after the implementation of miscible CO2 flooding, the injectivity and the oil production are significantly improved, the reservoir producing degree are increased and the structural high and artificial fracture strikes are the predominant directions; miscible CO2 flooding can replenish energy for strong water-sensitive reservoirs effectively, so it could be a new method to improve development effect and enhance oil recovery