The invention discloses an in-layer authigenic gas and gel combined profile control and flooding method. The method comprises the steps that an authigenic gas formula system and a gel formula system which are suitable for a target oil field are preferably selected; according to the channeling situation, the development situation, the injection amount per day, the injection pressure and the crude oil viscosity of a target reservoir, the combination mode of authigenic gas and gel is designed, the size of each slug is designed, and accordingly formula components in the slugs are determined correspondingly; the medium-high viscosity gel formula components are injected into the target reservoir; the low-viscosity gel formula components are injected into the target reservoir; the authigenic gas formula components are injected into the target reservoir; the steps are repeated, and the repeated time is determined according to the total injection amount and the size of each slug; and the medium-high viscosity gel formula components are injected into the target reservoir for insulating subsequent injected water. The in-layer authigenic gas and gel combined profile control and flooding method is based on the authigenic gas components and the gel components, besides the function of each components, the authigenic gas components and the gel components are combined to form a novel profile control and flooding system with the synergistic effect and adduction synergism, and thus the functions are strengthened.