The invention relates to a new molecular identification method for identifying trichosanthin and its similar products; adventurous innovation is made in two key links of primer design and annealing temperature. Primer design is performed on a known ITS of trichosanthin medicinal materials; the length is about 20 bp; and general primer design principles are followed. Meanwhile, the annealing temperature is screened and determined according to the number of polymorphism strips. The characteristic identification strips of trichosanthin are determined to be 560, 960 bp strips, and 1930, 1400, 839, 715 bp strips are considered as auxiliary identification strips of trichosanthin. The invention has the following advantages of: (1) simplicity and practicality, wherein although the difficulty for primer design is increased slightly, the specificity is greatly improved, an ideal identification primer can be obtained after design of 2-3 primers, and thus the problem of large screening of random primers is avoided; (2) stability and repeatability, wherein since the specificity and annealing temperature of the primer are improved, the amplification strips are generally only 1-5 strips, and certified products with different producing areas and different storage time have no effect on PCR results; (3) large provided information content, wherein both certified products and most fake products can be amplified simultaneously, and thus standard identification electrophoretograms of the certified products and fake products can be established to realize accurate identification of the certified products and fake products.