The invention provides a gemini surfactant, and a preparation method and application thereof. The gemini surfactant has high surface activity and good foaming ability and foam stability; and when applied as an air entraining agent for concrete, the gemini surfactant has good air entraining and foam stabilizing performance, allows hardened concrete to have a good pore structure, and pose little influence on the hardening strength of the concrete. The gemini surfactant has a specific structure; that is, the molecule of the gemini surfactant contains two hydrophobic chain segments and two hydrophilic units, wherein the hydrophobic chain segments are straight-chain alkyl chains with 8 to 18 carbon atoms, the hydrophilic units are quaternary ammonium salt groups, and the hydrophobic chain segments and the hydrophilic units are covalently connected through bridging units having large aromatic ring structures at positions close to a quaternary ammonium salt.