The invention discloses a waterproof and heat-preservation structure for a colored steel roof and a construction method of the waterproof and heat-preservation structure and relates to roof structures. The waterproof and heat-preservation structure for the colored steel roof improves the waterproof and heat-preservation property between every two adjacent colored steel plates of the roof. According to the technical key points, the connecting position of every two adjacent colored steel plates is provided with a connecting plate, and the upper ends of the connecting plates are slidably connected with waterproof plates extending out of the connecting plates through sliding blocks; the sides, making contact with the connecting plates, of the waterproof plates are provided with sliding grooves for inlaying of the connecting plates, and the groove bottoms of the sliding grooves are connected with pushing plates through a plurality of first compression springs; and the upper end surfaces of the connecting plates are provided with obliquely downward oblique planes, and when the first compression springs are in an initial state, the pushing plates abut against the lower sides of the oblique planes.