Objective To analyze the genetic type of NJS and its relative mice.Methods Five 10bp random primers were used to amplify DNA of NJS and its relative mice and DNA analyzed among individuals in the population of NJS.Results There were several fragments of genetic DNA shared by two mice but specific fragments were seen.Different individual NJS had various bands,but the frequency of common bands was high.Based on RAPD patterns,similarity index(F) was 0.927(0.880-0.980).Conclusion RAPD could be used to distinguish NJS and its relative mice. There is higher degree of homogeneity and stability in heredity among individuals in the population of NJS and the degree of population differentiation is at a lower level.