Abstract: Objective Genetic relationship and diversity of early and middle maturity potato varieties (strains) were studied using ISSR markers in order to provide references for early and middle maturity potato breeding parent selection in southern winter-cropping areas. MethodEight screening ISSR primers were used to assess the genetic diversity among 33 potato varieties (strains) planted in different areas of Guangxi.ResultThe results showed that 8 primers amplified 46 bands, out of which 29 bands were polymorphic, and the percentage of polymorphic loci was 63.0%. Genetic similarity coefficient of 33 potato varieties (strains) changed from 0.63045 to 1.00000, with an average of 0.80967. Cluster analysis results indicated that the potato varieties (strains) could be classified into four groups at 0.79000 similarity level. The first group included DE03-34-6, JL03-786, Zhongshu 19 and Zhongshu 18. Only Zhongshu 6 was in the second group. The third group contained Longji 1 and DE03-79-1. The rest varieties (strains) were clustered into the fourth subgroups. Varieties with close affinity (like Zhongshu 13&Zhongshu 14, Zhongshu 18&Zhongshu 19) could be clustered into close groups, which meant that potato va-rieties could be precisely clustered using ISSR markers. ConclusionThe tested 33 potato varieties (strains) have abundant genetic diversity. Parents can be selected by genetic distances of cluster analysis, which could provide references for early and middle maturity potato breeding parent selection and heterosis utilization in southern winter-cropping areas.