In order to overcome the shortcomings of common methods for evaluating the performance of injected fluids and realize the effective evaluation of the process of injected fluids flooding in tight reservoirs，three self made microfluidic models，including two dimensions porous media model，two and half dimensions throat model and semi-circle multichannel model，were used to online characterize the oil displacement property of nano fluidity modifier for tight reservoir. The results showed that the nano fluidity modifier could greatly decrease the water flooding start-up pressure and enter the smaller pore easier. The nano fluidity modifier divided the crude oil into smaller oil drop，thus significantly increased the fluidity and migration ability of crude oil with above 90% oil displacement efficiency，which could be expected to help the development of tight oil.