The invention discloses a method for preparing spherical cross-nickel hydroxide nano sheets in one step based on a porous nickel skeleton. The method comprises the steps that nickel powder and solublesalt are ground, uniformly mixed, pressed into semifinished products, placed in an inert atmosphere for sintering, and placed in the water for heat reservation for a period of time to obtain the spherical cross beta-Ni(OH)2 nano sheets taking a porous nickel template as a substrate. Compared with traditional nickel foam (pore diameter 100-200 microns), the pore diameter of the novel porous nickeltemplate is only 1-2 microns, the larger specific area of the novel porous nickel template facilitates large amount of loading of active substances, and the novel porous nickel template has larger application prospect in the fields of sensing and energy, particularly when the novel porous nickel template is used as a positive electrode material of a nickel-metal hydride battery. The method has the advantages of being simple in operation, green and environmentally-friendly, mild in reaction conditions and suitable for massive production. The spherical cross beta-Ni(OH)2 nano sheets are uniformly distributed on the skeleton of a porous nickel template, grain size is distributed uniformly, surface microstructure is diversified, the specific area is large and improvement of electrochemical performance is facilitated.