The invention relates to a light wave stealth device and invisible space expansion method. One end of a pedestal is provided with a front V-shaped prism, the other end of the same is provided with a back V-shaped prism whose structure is identical with that of the front V-shaped prism, an V-shaped opening of the back V-shaped prism faces an V-shaped opening of the front V-shaped prism, the front V-shaped prism is symmetrical by taking a middle vertical plane as the center, the middle vertical planes of the front and back V-shaped prisms are positioned in the same plane, a left prism and a right prism which are the same in structure and symmetrical by taking the middle vertical plane of the front V-shaped prism as the center are arranged between the front and back V-shaped prisms, the leftprism is opposite to and in parallel with the right prism, a space formed by the bottom side of the left prism, the plane where the two side surfaces of the left prism are positioned, the bottom sideof the right prism and a plane where the two side surfaces of the right prism are positioned is an invisible space a, and the invisible space a in the stealth device can be expanded by increasing distances between the front V-shaped prism, the rear V-shaped prism, the left prism and the right prism at the same time. An object can be invisible by being moved into the invisible space a.