Through analy sis on root system,soil antiscour,antierosion and shear strength determination of slope protection plant on the Nenjiang dyke,the results show that,in a same section,soil antiscour and antierosion (water stablility)index and shear strength of surface soil layer are all larger than that of base soil layer.Plant root system has rather pow-erful strength of soil-fixation function,the antiscour index has clear coherence with root length and root quantity, the single cohere coeffcients are 0.9146 and 0.8197 respectively.Soil antierodibility is better and water-stable index are bigger as soil o rganic mat tercontent is higher,the cohere coefficient between them is 0.9132,the cohere coefficient of it with root lenght and root quantity are comparatively rather low,the single cohere coefficient are 0.8317 and 0.8091.Plant root quantity has a great bear ing upon soil stability,the cohere coefficient of it with shear strength is 0.9814.In the plants now available on Nenjiang dyke,the antierodibility of Carex duriuscula C.A.Mey is greatest,its soil-fix ation and dyke revetment and slope revetment function are most strong,so it should be given a energetic spread in the same areas.