The invention relates to a preparation method of 1,1'-dialkyl-3,3'-(2-phosphate-1,3-propylene) imidazole inner salt compound. The 1,1'-dialkyl) 3,3'-(2-phosphate-1,3-propylene) imidazole inner salt compound of the present invention is an amphoteric gemini surfactant, and the specific synthesis method includes 1, Synthesis of 3-dichloro-2-propanol, synthesis of N-alkylimidazole, 1,1'-dialkyl-3,3'-(2-hydroxy-1,3-propylene)imidazole hydrochloride The synthesis of the salt and the synthesis of the 1,1'-dialkyl-3,3'-(2-phosphate-1,3-propylene) imidazole inner salt are four steps. The 1,1'-dialkyl-3,3'-(2-phosphate-1,3-propylene) imidazolium internal salt of the present invention and the preparation method thereof have easy-to-obtain raw materials, easy-to-control reaction process conditions, and easy operation. Simple, the product is easy to purify, and the yield is high. The substance has a low critical micelle concentration and is useful as a wetting agent, emulsifier, foaming and foam stabilizer. The macrocyclic imidazole head group and phosphate group in the molecular structure make it have good thermal stability, solubility, salt resistance, temperature resistance and acid and alkali resistance.