The invention relates to the technical field of building materials and in particular to a water purifying particle for concrete and a preparation method thereof. The water purifying particle comprisesa particle with a purifying function and a starch membrane positioned on the outer surface of the particle with the purifying function. The preparation method for the water purifying particle comprises the following steps: after washing the particle with the purifying function clean, drying, and cooling to room temperature; enabling modified starch to be dissolved in a solvent, to obtain starch membrane solution of which a mass fraction is 5%-15%; uniformly spraying the starch membrane solution on the outer surface of the particle with the purifying function, performing rapid drying treatment, forming the starch membrane, and preparing the water purifying particle. The water purifying particle is capable of, while applied to the concrete, effectively solving problems in the prior art thatthe concrete is easily blocked, service life is short and the like, improving a porosity of the concrete, and has lasting good water permeability.