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.