In order to clarify the distribution of residual oil in reservoirs with fining-upward，coarsening-upward，and superposition sequences in G Oilfield after polymer flooding，and to provide a reliable basis for residual oil recovery，water flooding and polymer flooding experiments were carried out in the three-dimension heterogeneous models according to reservoirs with different sequences. The experimental results show that：in the fining-upward sequence，the high-permeable layer at the bottom was flooded badly，and the swept volume in low-and medium-permeable layers was enhanced obviously after polymer flooding. Compared with water flooding，the average recovery rate in early stage increased by 3.4 times and oil recovery increased by 22.2%，the residual oil mainly distributes at the top of low-permeable reservoir near the corner production well in inverted nine-spot well pattern，and the horizontal adjustment well should be deployed at the top of reservoir to produce the residual oil；in the coarsening-upward and superposition sequences reservoirs，the modelled water flooding was more uniform in the vertical direction，and the swept volume can be further enlarged after polymer flooding. Compared with water flooding，the recovery rate in early stage increased by 2.3 times and 2.1 times，respectively，and the oil recovery enhanced by 18.5% and 18.1%，respectively. The remaining oil mainly distributes at the unswept area near the corner production well，and the directional adjustment well should be deployed to produce the residual oil. After the research result was applied to the field test of G Oilfield，the initial daily oil production of the adjustment wells was 2-3 times those of the old production wells nearby.