The wettability and microstructure characteristics can be changed by molecular film technology through injecting molecular film reagent into the reservoir micro pores, and the purpose of reducing injection pressure and improving water injection total is achieved. The adsorption capacity comparison between molecular films to rock surface with water molecular to rock surface was studied, and it was revealed that the molecular film took advantage in competition, then adsorbed in rock surface and formed molecule layer. Based on it, the application conditions and its change rules were explored then the molecular drag reduction mechanism from reducing the boundary layer effect and friction was revealed. At the last the property of the molecules film drag reduction was studied.