The invention provides a nickel-hydride secondary battery and a preparation method thereof. The preparation method of the nickel-hydride secondary battery comprises the following steps of: providing an anode piece, a cathode piece, electrolyte and a diaphragm, coiling the anode piece, the cathode piece and the diaphragm into cylinders, feeding the cylinders into a battery shell, injecting the electrolyte, and performing sealing treatment, wherein a preparation method of the anode piece comprises the following steps of: providing anode raw materials including spherical Ni(OH)2, a pore forming agent and an anode additive, mixing the anode raw materials so as to form an anode material, filling the anode material to an anode conductive substrate, and pressing and cutting by using a twin roller so as to obtain the anode piece; and/or a preparation method of the cathode piece comprises the following steps of: providing cathode raw materials including a rare earth based-hydrogen storage alloy, a pore forming agent and a cathode additive, mixing the cathode raw materials so as to form a cathode material, filling the cathode material onto a cathode conductive substrate, and pressing and cutting by using a twine roller, thereby obtaining the cathode piece.