Abstract: To obtain pure mycelia before DNA extraction,Armillaria mellea(Vahl.ex Fr.)Quel collected from the field need to be isolated.Traditional liquid culture purifying method has the disadvantage of low efficiency.Although pure mycelia can be collected from cellophane film on solid medium,it is difficult to obtain sufficient materials for DNA extraction.We therefore put forward a modified method that is extracting DNA from rhizomorph of A.mellea cultured by solid agar medium.The results show that agar around the rhizomorph materials can be mostly removed when samples were pretreated via freezing-melting.DNA extraction buffer mixed with KAc solution(1.25 mol/L) can effectively eliminate agar and other polysaccharid residuals.The quality of extracted DNA was then tested by a series of measures,including ultraviolet absorption test,agarose gel electrophoresis,amplification by using ISSR primers and digestion by restriction endonuclease Mse I.The results confirmed that the quality of extracted DNA using this modified method is very high,and proven to be suitable for further molecular analysis.