The invention provides a water-stop strip, a water-stop structure of the water-stop strip, and a construction method for the water-stop structure. The water-stop strip is made of elastic materials. The whole water-stop strip is in a strip shape and comprises a plug, a left side wing and a right side wall. One end of the left side wing and one end of the right side wing are connected to the second end of the plug. An included angle alpha is formed between the left side wing and the plug. An included angle beta is formed between the right side wing and the plug. A groove seam is formed in the end face of the second end of the plug. In the water-stop structure, the water-stop strip is arranged in a surface seam in an upstream face of a preset object; the plug of the water-stop strip of the water-stop structure is embedded in the surface seam; the left side wing and the right side wing cover the two sides of the surface seam; and the two side wings and the surface of the preset object are bonded through polymer structure glue playing a sealing role so that covering of the surface seam and sealing water stop can be achieved. The water-stop structure can bear the water pressure of a 100m water head and can bear the situation that joints are opened by 2 cm. The water-stop strip is formed at a time through a special mold and is high in quality, low in manufacturing cost, convenient to transport, beneficial to construction and installation. The finally constructed water-stop structure is safe and reliable in water-stop effect and low in expense.