A method for producing polyploid plants of orchids includes the steps of: providing a protocorm or protocom-like body (PLB) of an orchid, the protocorm or PLB having an upper portion with a growing point and a lower portion without any growing point; cutting the protocorm or PLB approximately at a point of half height to separate the upper portion; subculturing the lower portion of the protocorm or PLB in an inducing medium, and putting a cut surface of the lower portion of the protocorm or PLB to face upward so that one or more next-generation PLBs grow from the cut surface of the lower portion. The method characterized in using no antimicrotubule agent can simplify the entire process of orchid polyploidy breeding, and can be used in mass-production of the stable polyploid plants.