Since amounts of residual oil still remains after dissolved gas drive in super heavy oil reservoir，effects of flooding conversion on oil displacement efficiency were studied through experiments under various conditions focusing on this problem. The lab experiment results illustrate that the oil recovery by the traditional dissolved gas drive for homogeneous lab core model is about 10%. Either steam stimulation or CO2 stimulation after dissolved gas driving stimulation can enhance oil recovery to some extent. Steam stimulation is more applicable with a final oil recovery of more than 70%，whereas the oil recovery after CO2 stimulation can only achieve about 25%. Additionally，the influences of the pressure drop speed，temperature and permeability on oil recovery are different. A faster pressure drop can lead to a faster recovery speed and enhance recovery efficiency for a certain time. The oil recovery is controlled by temperature with time effect. Lower temperature can enhance oil recovery. The effect of formation permeability on the oil recovery is limited，and a higher permeability can boost recovery speed.