The method for producing polyploid plants of orchids in accordance with the present invention is intended in physical cutting the protocorms or protocom-like bodies (PLBs) of orchids at a predetermined position thereof, and culturing the protocorms or PLBs in a medium to induce a new next-generation PLBs by means of plant tissue culture techniques. When growing up to a predetermined size, the new next-generation PLBs are cut off and processed by further cutting and culturing them so as to increase the number of PLBs and to have a high frequency of polyploidy. Subsequently, the new next-generation PLBs are cultivated in a regenerating medium so as to differentiate the next-generation PLBs into plantlets. Furthermore, a flow cytometer is used to process a chromosome ploidy analysis in identifying the ploidy level of the plantlets.