The invention relates to elastic concrete for caulking bridge expansion joints, which is characterized by comprising the following components in part by weight: 400 to 500 parts of cement, 100 to 600 parts of sand, 200 to 1,000 parts of stone, 100 to 500 parts of rubber particles, 20 to 300 parts of emulsified rubber, 0 to 3 parts of distearoyl isopropoxy, 0 to 3 parts of vinyl triethoxysilane, 0 to 3 parts of lignin coupling agent, 0 to 3 parts of isopropyl-32-octyl phosphate acyloxo and water, wherein the in a water to cement ratio is 0.4 to 0.5. A preparation method comprises the following steps: cleaning and treating the surface of the rubber particles with a sodium hydroxide solution at the concentration of 1 percent; adding the coupling agent into a container in the water bath at the temperature of between 40 and 60 DEG C, then adding anhydrous ethanol into the container, and stirring the mixture until the coupling agent is dissolved in alcohol completely; putting the rubber particles in a stirring machine, heating the rubber particles to the temperature of between 60 and 70 DEG C, stirring the rubber particles, adding the diluted coupling agent into the rubber particles gradually, stirring the mixture for 10 minutes, taking the rubber particles out and drying the rubber particles at room temperature; and putting raw materials into a concrete stirring machine, stirring and adding emulsified rubber emulsion into the concrete stirring machine. The prepared elastic concrete has the advantages of high deformation and great strength resistant to impact and abrasion and has good effect in application in the bridge expansion joints.