Abstract: Malus hupehensis Rehd. seedlings were planted in pot and residual roots were added to pots filled with replant soil at four rates（w/w）：0，0.3%，0.6%，1.2% and 2.4%. The effects of residual roots on the biomass of M. hupehensis Rehd. seedlings and soil environment were measured. The results showed that 0.3% increased the biomass of the seedlings，while when the residual roots application was between 0.6%–2.4%，the biomass of seedlings were decreased. The number of soil microorganism were also changed by the residual roots，in spring，compared with the control，the treatments of 0.6%，1.2% and 2.4% decreased the number of bacteria by 19.36%，30.78%，39.6%，respectively，but the numbers of fungi and actinomycetes were increased. The similar trend was observed in summer and autumn. The addition ofresidual roots significantly increased the content of phenolic acids，in spring，the treatments of 0.6%，1.2%，2.4% increased the content of phenolic acids by 57.49%，116.20%，131.718%，respectively. In addition，the treatments of 0.6%，1.2%，2.4% decreased the activities of soil urease and sucrase，and increased the activities of soil neutral phosphatase. These results suggested that the residual roots on the growth of M. hupehensis seedlings depended on the concentrations of its application，lower addition of residual roots could promoted the accumulation of plant biomass，while higher concentration of residual roots led to serious growth inhibition for M. hupehensis seedlings，which was responsible for the continuous cropping obstacle.

Key words: Malus hupehensis, root residue, replant disease；microbe；soil enzyme activity, phenolic acid