Abstract: The random amplified polymorphic DNA(RAPD) analysis was applied to identify the resources of medicinal plant Gynostemma pentaphyllum and its spurious breed with DNA fingerprints.The modified CTAB method was used to extract the genomic DNA of several plants,including seven leaves Jiaogulan,five leaves Jiaogulan,Cayratia japonica.With the DNA extracted from seven leaves Jiaogulan as template,the random primer WGS001 for PCR has been done meanwhile RAPD reaction system has been optimized so that it could be determined for the suitable annealing temperature and concentrations of template,Mg²⁺,primer,Taq DNA polymerase,BSA.In the optimized system of 25 μL,MgCl₂ 2 mmol/L,primer 0.4 μmol/L,template 60 ng,Taq DNA polymerase 1 U,BSA 2 μg/μL and annealing temperature 58℃ were used.Based on the optimized system,ten primers of 20 bp were applied to do random amplification with total DNAs of the above mentioned three plants,respectively.The polymorphic fragments of DNA fingerprints of the above mentioned three plants were obtained with two screened random primers(WGS001,WGS004).These polymorphic fragments can be used to distinguish G.pentaphyllum with C.japonica obviously.