There are plenty of dead-end pores in low permeability reservoirs，in which crude oil is hardly initiated by water flooding. As a result，oil in dead-end pores is a kind of residual oil after water flooding. The microscopic dead-end model is made by glass etching. Laboratory experiments are conducted to simulate the reservoir development，including water flooding，CO2 immiscible flooding and CO2 miscible flooding under the condition of saturated oil. With the help of microscopic and visual system，the initiating characteristics of the residual oil in dead-end pores by different displacement methods are observed. Experimental results show that water could only enter the shallow area of the dead-end pores，and residual oil is hard to be initiated. Moreover，supercritical CO2 could penetrate into the dead-end pores，and parts of residual oil is initiated and driven out along the glass wall，and enters into major channel after CO2 immiscible flooding. Furthermore，the supercritical CO2 could displace the residual oil in deep pores at the dead end，and all of the residual oil could be displaced with the increase of the CO2 pore volume after CO2 miscible flooding. The analysis indicates that extremely limited residual oil in dead-end pores can be displaced with the help of pressure change and fluid compressibility by water flooding. However，the supercritical CO2 will exchange some components of the residual oil continuously，and enters into the dead-end pores through fluid mass transfer，and then a large amount of residual oil is displaced. Therefore，the supercritical CO2 not only has a high oil displacement efficiency in the live pores swept by conventional displacement fluid，but also could displace the residual oil in the dead-end pores. In other words，supercritical CO2 could reduce the residual oil saturation and enhance oil recovery.