Abstract: Aiming at the problems of poor injectivity and worse migration of common foam, microfoam with tiny diameter is prepared by co-flowing gas and foaming agent to sand pack pipe foaming generator. The differences of injectivity and profile control of microfoam and common foam were compared by testing multiple pressure of long sand pack and parallel sand packs. Plugging mechanism and effectiveness in improving profile control capacity of microfoam and common foam were evaluated by micromodel tests. The results show that bubble diameter of microfoam is less than the pore throat diameter of high permeability area, the flow resistance of bubble is lower. Microfoam would block pore throat of high permeability area through the way of bubble accumulation, subsequent bubbles would flow into low permeability area with the way of directly through or elastic deformation, and a small number of bubbles could block small pore throat through the way of bubble trapped. However, the microfoam accumulated in the high permeability area is easily dispersed, resulting in a weak blocking strength and limited profile control ability. Compared with microfoam, bubble diameter of common foam is more than the pore throat diameter in high permeability area, flow resistance is greater and plugging ability is stronger, the bubbles mainly flew through the way of elastic deformation and liquid membrane differentiation into the pore throat. Profile control capacity of common foam is better at the same foam injected volume. Microfoam could produce more uniform differential pressure across the sand pack, and its injectivity and deep plugging ability are better than the common foam, but the capacity of blocking high permeability channel, water flushing resistance, and profile control is weaker.