The invention discloses an adhesive for a solid wood floor and a preparation method of the adhesive. The adhesive is a one-component moisturecuring polyurethane elastic adhesive which consists of polyether polyol, polyisocyanates, a plasticizer, padding, a catalyst, a water removing agent, a coupler and an antioxygen. The adhesive used to pave the solid floor overcomes the deficiencies that at present, in solid wood floor pavement, the solid wood floor is large in noise, free from elasticity, poor in stability, has sound like an empty drum, and cannot be used in a ground heating system and the like due to rough grounds which have to be used. The adhesive has the advantages of one-component moisturecuring, convenience in operation, strong adhesive strength, safety, environment friendliness and the like, and can be adjusted in different colors according to colors of the solid wood floors. The solid wood floors paved have the advantages of elasticity, comfort, low noise, and can be used in the ground heating system and the like, and the risk of deformation and crack of the solid wood floor can be reduced. The adhesive is suitable for paving various solid wood floors and elastically adhering skirting lines, thresholds and stairs and the like, and meanwhile the adhesive is further used for paving ceramic tiles.