Abstract:The SCoT-PCR system for Carica papaya was optimized by using single factor experiment method, such as Mg2+, dNTPs, primer, Taq polymerase and DNA template, and the SCoT primers were selected with optimized system. The results showed that the optimum concentrations for Carica papaya SCoT-PCR amplification were 2.0 mmol L-1 Mg2+, 0.3 mmol L-1 dNTPs, 0.8 μmol L-1 primer, 1.0 U Taq polymerase, and 30 mg L-1 template DNA in total 20 μL reaction system, respectively. The optimum SCoT-PCR system was tested on 22 varieties of Carica papaya by different SCoT primers, obtaining steady, reliable and high resolution bands. Five primers and five pairs of primer combination were selected with abundant polymorphism. It was suggested that the optimum SCoT-PCR system and polymorphism primers could be used in the germplasm identification and genetic diversity analysis of Carica papaya.