Abstract: Old apple orchard with soil potted Malus hupehensis Rehd. seedlings as test material，the effects of matrine on seedling growth and soil microbial population were studied. The results showed that in September，compared to the control group，adding 0.01% matrine to the soil can significantly improve plant height，ground diameter，dry weight，root surface area，root volume and root respiration rate of Malus hupehensis Rehd. seedlings，and the activities of root SOD，POD and CAT were also significantly improved. After matrine treatment，the number of bacteria and fungi in soil decreased，the decline of fungi was greater than that of bacteria，and the ratio of bacteria to fungi increased. The bacteria and fungi treated with 0.01% matrine decreased by 58.5% and 68.3%，respectively，and the ratio of bacteria to fungi increased by 30.6%. The Shannon index and Margalef index of microbial diversity in soil treated with matrine were significantly reduced，and the gene copy numbers of Fusarium solani，Fusarium proliferatum，Fusarium moniliforme and Fusarium oxysporum were reduced by 51.2%，43.3%，40.0% and 44.5%，respectively，compared with the control. In conclusion，0.01% matrine treatment promoted the growth of Malus hupehensis seedlings，improved the soil environment，and effectively alleviated the replant disease of Malus hupehensis.

Key words: Malus hupehensis, old apple orchard, replant disease, soil, matrine