The invention discloses a heat insulation and waterproofing device at PC wallboard vertical joints and an application method of the heat insulation and waterproofing device. The heat insulation and waterproofing device includes steel plates, sealing plates, compressed springs and thickness adjusting assemblies, wherein the sealing plates are made of extrudable deformation materials, the two steelplates are arranged in parallel, the outer parts of the steel plates are attached to the sealing plates with the same plane size, and a plurality of compressed springs and thickness adjusting assemblies are arranged between the two steel plates; and the vertical joint sides of PC wallboards are prefabricated into U-shaped tongues-and-grooves, and L-shaped steel plates are pre-embedded in the two sides of the U-shaped tongues-and-grooves. After reducing the thickness of the device and inserting the device between the two adjacent U-shaped tongues-and-grooves, the sealing plates on the two sidesof the device are extruded and attach to the side walls of the U-shaped tongues-and-grooves through elastic reset of the device to form a waterproof barrier, foam glue is poured between the steel plates on the two sides of the device to form a heat insulation layer, finally, after the joints on the two sides of the device are filled with sealing materials, sealant is used for jointing and sealing, and two waterproof barriers are formed by the foam glue and the sealant. The device is simple in structure, and the problems of rainwater leakage and heat insulation at the vertical joints of the PCwallboards are completely solved.