Abstract: Abstract: The reaction and population dynamics were studied between the resistant cultivar Yingxian small black soybean and Heterodera glycines race3(SCN3). The results showed that Yingxian small black soybean was against the development of SCN3, especially J2 to J3 and J3 to J4; and the ratio of female-male was affected. Most of J4 found in resistant cultivar was male, the female was extremely little, but SCN3 was developed normally in the susceptible cultivar Liaodou15 and most of the J4 was female. Cryo-sectioning technique was used to observe the resistant cultivar and susceptible cultivar. The different soybean cultivars existed different resistant mechanisms to the SCN3. The histopathological responses to the SCN3 showed that the adjacent necrosis and the lignifications to the bodies of juveniles was occurred in the roots of resistant cultivar Yingxian small black soybean ,whereas the necrosis was not found in the susceptible cultivar Liaodou15. The syncytia was founded in the root of the resistant cultivar.