The invention provides a low-modulus high-adhesion assembling type silane modified polyether adhesive used for a building. The low-modulus high-adhesion assembling type silane modified polyether adhesive is divided into a component A and a component B, wherein the component A comprises silane modified polyether, a plasticizer, hydroxyl-terminated branched polyether, branched polyether epoxy resin,a coupling reagent, a thixotropic agent, white carbon black, enhanced filler A, hollow glass microsphere and toner; the component B comprises the plasticizer, the hydroxyl-terminated branched polyether, a light stabilizer, enhanced filler B, an organic tin catalyst and an amine curing agent. In addition, various ingredients in the silane modified polyether adhesive are optimized to obtain a sealant formula with an optimal binding effect. The double-component polyether adhesive system has good compatibility, in addition, the adhesion of the double-component polyether adhesive is greatly improved, the double-component polyether adhesive system is applied to the prefabricated construction member material abutted seam connection used by the assembling type building, a good binding and waterproof effect can also be achieved without being cooperated with a first coat, and meanwhile, a water leakage risk brought by an existing first coat construction misoperation can be avoided.