Absract: SSR (simple sequence repeat) and SRAP (sequence-related amplified polymorphism) were employed to study their genetic diversity and genetic relationship. Three conclusions can be drawn from this study: (1)29 SSR primer pairs generated a total of 121 apparent DNA fragments. The polymorphic bands took 97.5% of total amplified bands.27 SRAP primer pairs generated a total of 175 apparent DNA fragments. The ratio of polymorphism is 70.3%. (2)The result of two labels mixing analysis indicated that all tested-cultivars can be classified two groups at 0.566 similarity index level. And B group can be classified six sub-groups at 0.62 similarity index level. The first group contained 10 natural double low B. napus L strains with extreme early maturity, 2 parents of B. napus L and four new B. napus L strains which were created by four D9946 and HAOYOU11 . The other 51 new B. napus L strains were classified into 5 different sub-groups. (3)The genetic element of 55 new strains was analyzed, which indicated that the ratio of different bands in different strains that accounted for all bands was different. The correlation analysis between the ratio of special bands of parents of B. campestris L in new strains and the genetic distance between new strains and their parents, respectively. It showed that it was negative correlation (-0.52) and positive correlation (0.31) between special bands of parents of B. campestris L in new strains and the genetic distance between new strains and their parents of B. campestris L and B. napus L, respectively. （4）The genetic distance and origin of all the materials except two parents of B. campestris L were analysized that genetic distance that ranked top 20 were among that of new B. napus L strains of extreme early maturity or that between new B. napus L strains and natural B. napus L strains of extreme early maturity. The largest genetic distance was up to 0.544.