Abstract: The original natural elastic energy of reservoirs are main energies for tight reservoir development and the ultimate recovery factor is generally less than 10%. Air foam flooding can replenish energy for tight reservoir development to improve the ultimate recovery factor. Based on experiments with single-barreled cores and double-barreled cores, the paper studies flow characteristics and displacement effect in tight reservoirs by air foam flooding, discusses the influences of different factors on the air foam flooding effect and concludes that the optimal gas-liquid ratio is 3:1 and the optimal size of foam liquid slug is 0.05 PV. The results show that the air foam flooding can obviously improve oil production and good water control effect can be gained. Taking 15 typical producers as examples, the average oil production per month is 198.1 t and 240.0 t before and after injection, respectively, and the oil production is increased by 21%; the average water cut is 28.8% and 28.9% before and after injection, respectively, and the water cut only increases by 0.1%