A preparation method of iron-nickel loaded nano calcium peroxide used for micro-polluted water treatment comprises the following steps in turn: adding iron-nickel hydrotalcite powder into a 0.2-0.8 mmol/L sodium valerate solution, and stirring in a 50-70 DEG C water both for 2-4 h; adding disodium EDTA, stirring in the water bath for 2-4 h, filtering the product, washing with distilled water, draining, oven-drying at 105 DEG C, and calcining at 300-500 DEG C for 30 min to obtain calcium oxide post-supported iron-nickel hydrotalcite; and sieving 30 g of calcium oxide post-supported iron-nickel hydrotalcite with a 20-30 mesh sieve, adding into 40-50 mL of 10% (wt%) hydrogen peroxide solution, reacting in a 4-5 DEG C water bath for 4-5 h, separating solid precipitate and liquid, washing the solid with deionized water for 3-5 times, and oven-drying at 105 DEG C to obtain the nano calcium peroxide used for micro-polluted water treatment. The iron-nickel loaded nano calcium peroxide of the invention has the characteristics of hydrotalcite, and has large specific surface area, and strong adsorptivity and catalytic oxidizability.