Abstract: The biological changes in continuous soybean by soybean intercropped with Chinese onion(Allium fistulosum L.),potato(Solanum tuberosum L.),hemp(Cannabis Satia L.) and tobacco(Nicotiana tabacum L.) were investigated in a long-term continuous soybean Mollisols field of Northeast China.The results indicated that compared with soybean monoculture,the yield of continuous soybean was increased by 12% and 9% in Chinese onion/soybean and potato/soybean intercropping systems while it was decreased by 18% and 7.6% in hemp/soybean and tobacco/soybean intercropping systems.Disease severity index of root rot in continuous soybean was decreased by 18.3%,28.5% and 34.2% respectively with increased control effect in Chinese onion/soybean,potato/soybean and tobacco/soybean intercropping systems while it was increased by 10.3% in hemp/soybean intercropping system.Above ground dry matter accumulation at later stage of soybean growth and yield components were all increased significantly in Chinese onion/soybean,and potato/soybean intercropping systems.We conclude that Chinese onion/soybean and potato/soybean intercropping are of values in long-term continuous soybean farmland in Heilongjiang province.