The genetic diversity and genetic relationship of 24 Dendrobium candidum germplasms with different yields were studied by ISSR molecular markers in this study. Seven ISSR primers were screened to amplify genomic DNA of Dendrobium officinale by PCR. A total of 92 DNA bands were obtained, of which 84 were polymorphic, and the polymorphic ratio (PPB)was 91.3%.By POPGENE 32 analysis, the average of observed number of alleles(Na)is 1.913 0, effective number of alleles (Ne)is 1.528 3,Nei’s genetic diversity (H)is 0.310 0 and the Shannon’s information index(I)is 0.465 0. The genetic similarity (GS)of twenty four varieties by NTSYS-pc software ranged from 0.478 3 to 0.913 0. Cluster analysis showed that 24 cultivated populations of Dendrobium officinale could be divided into three groups. The results showed that the genetic diversity of Dendrobium officinale germplasm resources was abundant. It provides a reliable theoretical basis for comprehensively understanding the genetic background, the selection, introduction and promotion of Dendrobium officinale in this research.