Abstract: In this experimentation, the genetic diversity of poplar clones was studied by RAPD markers. The total DNA were extracted following a modification of CTAB method with some adjustments, influential parameters were optimized and the reaction system of PCR amplification was improved. On the basis of them, the genetic diversity of 13 poplar clones was studied by RAPD amplification with 18 primers. Each primer can produce 1 to 14 pieces of DNA fragments, of the total, 126 fragments were amplified. Among these, the number of polymorphic bands were 53, which occupied 42%, each primer can amplify 3 bands on average. It revealed that phylogenetic relationship was analyzed through cluster of bands in 126 amplified loci, RAPD analysis can examine lots of variations. Clone can be distinguished and purity can be measured by special bands. Molecular checking index was put forward according to special bands.