Random amplified polymorphic DNA (RAPD) was used to analyze genetic polymophism of 35Tree Peony cultivars with 7 different color groups. Thirty four primers amplified 418 DNA fragments and 337polymorphic bands (80.6%), including specific DNA markers for 18 cultivars that could be used to differentiate cultivars. The UPGMA method was used to analyze the genetic relationship among cultivars. The results showed that 35 Peony cultivars could be divided into 2 cluster groups when using similarity criteria of 1.5, and into 4 cluster groups when using similarity criteria of 1.0. The result confirmed that the flower color has no relation to the genetic clusters and the Tree Peony cultivars originated from the same area has close genetic relationship. Therefore, genetic background has no large effect on the genetic relationship. The sequence based on polymorphic rate from high to low was Blue groups ＞ Yellow groups ＞ Bark red groups ＞ Blake groups ＞White groups ＞ Green groups ＞ Red groups.