The invention discloses a method for inducing polyploid plants of hybrid orchids by using a compound mutagen. The preparation of the chemical mutagen, the selection and treatment of materials, the differentiation and cultivation of rhizomes, the morphological identification of mutant plants, the identification of stomata, and the identification of chromosomes , subculture, and finally determined to be hybrid orchid polyploid plants. The invention improves the mutagenesis rate of the hybrid orchid, the polyploid mutagenesis rate is increased by 10-20% on average, the highest death rate is 10%, and the chimerism rate is reduced by 10%. The invention has the advantages of reducing the formation of chimeras, increasing the mutation rate of polyploids, stabilizing polyploids after three generations, and shortening the identification time. The invention can increase the mutation rate of polyploid, reduce the damage to plants, and improve the survival rate of mutant seedlings. The dosage of Ansulphin and EMS is small, which can reduce the poison of chemical drugs and reduce the cost. And can effectively reduce the formation of chimeras and reduce costs.