Twenty inbreds were classified by RAPD markers(random amplified polymorphic DNA procedures). The materials included six main inbreds (Dan 340, Zi 330, 7922, Su37, 449 and Huangzaosi), which represented six main heterotic groups(Luda Red Cob, Lancaster, Reid, Suwan, Mobai and Sipingtou)of maize backbone inbred lines in karst high elevation mountainous area in China. Total 136 DNA polymorphic bands were produced from 21 primers which were screened out from 90 random primers, and an average proportion of polymorphic loci was 86.3%. Cluster analysis by unweighted pair group method of arithmetic means(UPGMA)suggested that 20 inbreds could be divided into 5 groups with genetic distance from 0.632.