Abstract: With 20 SRAP primers，263 bands were amplified in 81 Ricinus Communis varieties，among them 214 bands (81.37%) were polymorphism.The genetic similarity coefficients of 81 materials were ranged from 0.32558 to 0.92973，it shows rich genetic diversity in castor varieties.The clustering of 81 tested varieties showed that varieties used in the present study are divided into 4 groups (L1-1，L1-2，L1-3 and L1-4) at the dissimilarity coefficient threshold of 0.43.If the dissimilarity coefficient threshold was shift to 0.287，groups L1-4 was clustered two groups (L2-1 and L2-2 ).From the dendrogram，we know that the varieties which clustered together are from the same geographical region or were bred from the same breeding institute.The varieties in the same group have high similarity coefficient while two from differ groups have low similarity coefficient.The molecular cluster dendrogram provides a scientific basis for genetic breeding of castor cultivars germplasm.