Gemini surfactant flooding is a promising technique to enhance oil recovery from medium-high permeability oil reservoirs. The screening of the surfactants is mainly based on their capability of lowering the surface tension between oil and water. However, gemini surfactants with high capability of lowering the surface tension do not necessarily enhance oil recovery from low-permeability oil reservoirs. Based on the fractal analyses of low-permeability cores and molecular spacer group, the fluid mechanics of gemini surfactant flooding in low-permeability oil reservoir is discovered. The fractal dimensions of the spacer group of gemini surfactants should match the fractal dimensions of the pore structures of low-permeability oil reservoirs.