Genetic relationship and diversity of 22 papaya (Carica papaya L.) major cultivars in China were analyzed based on sequence-related amplified polymorphism (SRAP).(1)The 20 pairs of SRAP primers generated a total of 249 fragments,and polymorphic bands were 110 which accounted for 43.20% in the total amplified fragments.The number of amplified and polymorphic fragments was 12.45 and 5.50 per primer pair,respectively.(2)The polymorphism information content (PIC) values of these markers varied from 0.15 to 0.79,averaging 0.49.(3)UPGMA cluster analysis and principal coordinates analysis (PCOA) showed that the range of genetic similarity (GS) was 0.72~0.96 among 22 papaya cultivars with a low genetic diversity.All cultivars could be divided into three groups at the GS of 0.87.These results indicated that SRAP analysis could be used to reveal effectively the genetic relationships of papaya cultivars in China,providing a scientific basis for the classification,protection and effective utilization of these resources and breeding new varieties.