Abstract: The AFLP was used to study the genetic diversity of 19 potato cultivars. The result showed that 495 AFLP bands were amplified using 7 primer combinations, among them 302 bands were polymorphic, and 54~90 bands were amplified in each lane. AFLP analysis indicated the genetic distance of 19 potato cultivars was between 0.2091~0.7679, average value was 0.4811. When all of the polymorphic bands were analyzed by cluster analysis, 19 cultivars were classified into 4 groups. The numbere two groups included 14 potato cultivars, which accounted for 73.68%. The analysics showed that there existed close sibship among the majority of potato cultivars, and the genetic distance between the minority cultivars and the others is longer, which indicate that the genetic basis of KeXin series potato cultivars is wide. In addition, this study demonstrates that AFLP finger printing has higher resolution and the AFLP is more suitable in the diversity study of potato cultivars.