The invention relates to a preparation method of the seal glue of an inflaming retarding construction, which belongs to the technical field of the seal glue and comprises: at first, a first polylol and a second polylol are mutually mixed; then isocyanate and dibutyl tin laurate are added for reacting and preparing polyurethane prepolymer; then a terminated silane coupling agent is added for obtaining silane terminated polyurethane prepolymer; then the silane terminated polyurethane prepolymer is stirred mutually and mixed with dried nanometer fillings, a chemical inhibitor, a UV absorbent, a plasticizer, a thixotropic agent, dye and a flame retardant; then a deicer, a caking accelerant, and a catalyst are added, stirred and mixed for preparing the seal glue. The seal glue of the inflaming retarding construction does not have dissociative isocyanate, adopts halogen-free and inflaming retarding technology which is harmless to environment, producing and the health of users, has very good sticking performance with the materials such as glass, aluminum, marble, cement and the like, has good UV resistance and stability and can be broadly applied to the fields of construction, container, road, airport construction, and the like.