A piston-type water hammer absorber comprising: a cylinder body, a plug assembly and a piston; wherein a receiving cavity is formed in the cylinder body, and the piston is movably blocked in the receiving cavity; one end of the cylinder body is provided with a first opening and the other end is provided with a second opening, the first opening and the second opening respectively communicate with two ends of the receiving cavity, and an end of the cylinder body corresponding to the first opening is provided with a limiting part; and the plug assembly blocks the second opening, and a sealed cavity is formed between the plug assembly and the piston.