Abstract: The fresh leaves of Cynanchum atratum were used as experimental materials, and the DNA kit extraction method was used to study the effects of agarose gel concentration, sample volume, eluent volume and ethanol concentration on the extraction of genomic DNA from Cynanchum atratum,in order to obtain the most suitable extraction method of genomic DNA from Cynanchi atratum.The results showed that when the concentration of agarose gel was 0.8%,the amount of sample was 13 μL,80% ethanol was used for precipitation, and the amount of elution buffer was 100 μL,the electrophoresis band was the most clear and bright without tailing, which was the optimal method for genomic DNA extraction of Cynanchum atratum.In summary based on the kit method, the high purity of Cynanchum atratum DNA was obtained, which laid the foundation for the study of molecular biology and genetics of Cynanchum atratum,and provided reference for the development and utilization of authentic Cynanchi atratum medicinal resources.