The invention provides a slurry pump piston and a dismounting method thereof. The slurry pump piston comprises a piston rod, a piston head and a sealing assembly. The piston head is arranged on the outer wall of the piston rod in a sleeving mode. The sealing assembly comprises a sealing rubber sleeve, an upper slurry scraping ring and a lower slurry scraping ring. The upper slurry scraping ring and the lower slurry scraping ring are arranged outside the piston head in a sleeving mode, and an accommodating space is formed between the upper slurry scraping ring and the lower slurry scraping ring. The piston head is sleeved with the sealing rubber sleeve which is located in the accommodating space. The piston head is further provided with dismounting screw holes. The forming directions of the dismounting screw holes are parallel to the axis direction of the lower slurry scraping ring. The sealing performance of the piston is ensured, the arranging positions of parts of the sealing assembly are matched with those of the dismounting screw holes formed in the piston head so that the sealing assembly can be rapidly separated from the piston head by screwing dismounting parts into the dismounting screw holes, and therefore the dismounting time is shortened.