The nitrogen foam profile control and displacement technique is widely used in oil recovery，water control，and other enhanced oil recovery measures because of its characteristics of adjusting the fluid production profile and reducing the water cut. In order to furtherly clarify the applicable limit of nitrogen foam profile control and flooding system in medium porosity and medium permeability reservoir and to determine the best flooding time，the effect of the enhanced nitrogen foam on cores with various permeability ratios was evaluated，and the influence of heterogeneity and flooding time on profile control and displacement of the nitrogen foam system was analyzed by laboratory experiments. The experimental results show that for the medium porosity and medium permeability reservoir，the system has a better effect on water control and stable oil production，and the recovery efficiency by nitrogen foam flooding can be increased by more than 18%compared with that by water flooding when the permeability ratio is in the range of 2-6；among them，the recovery efficiency is the highest（20.0%）when the permeability ratio is 6. The production profile will be improved when the permeability ratio is about 3，and the diversion rate can be effectively controlled at 0.25 PV. When the water cut of the produced fluid is 80%，it is the best time for nitrogen foam flooding. The experimental results of enhanced nitrogen foam flooding for the reservoir adaptability can provide guidance for the optimization of water control and oil production increase measures and the design of foam flooding scheme in oilfield.