The invention discloses a novel anti-crack light core mold which comprises a light inner core block. An inner core of the light inner core block is made of foam materials, first glass fiber grid cloth is arranged on the surface of the light inner core block, a partition layer is additionally arranged on the upper surface of the first glass fiber grid cloth, second glass fiber grid cloth which wraps the upper surface and the side surfaces of the partition layer is additionally arranged on the outer side of the partition layer, and a waterproof layer is arranged between the partition layer and the additional second glass fiber grid cloth; two layers of reinforcing ribs are distributed inside the light inner core block from top to bottom and are arranged in a mutually crossed manner. A method for constructing the novel anti-crack light core mold includes constructing a bottom protective layer; laying a light core mold; fixing the light core mold; integrally pouring concrete. The novel anti-crack light core mold and the method have the advantages that the problem of cracking of the upper surfaces of existing light core molds, edge damage and corner falling at corners of the existing light core molds and the like even after anti-crack motor composite glass fiber grid cloth is smeared on the existing light core molds can be effectively solved, the construction quality can be guaranteed, and economic benefits can be increased.