Abstract: To provide a theoretical basis for clarifying the mechanism of apple replant disease，a pot experiment was conducted to study effects of phloridzin and Fusarium moniliforme on the growth of Malus hupehensis Rehd. seedlings and the replanted soil microorganisms. The determination results of the August showed that the biomass of M. hupehensis Rehd. seedlings was significantly reduced with the treatments of Fusarium moniliforme，phloridzin and Fusarium moniliforme + phloridzin. The plant height，ground diameter，fresh weight and dry weight of the Fusarium moniliforme + phloridzin were 70.6%，77.4%，52.3%，and 43.7% of the replanted soil control，respectively. The growth trend of the treatments in September was consistent with that in the year of August. Treatments that caused damage to the root respiration rate of M. hupehensis Rehd. seedlings in August and September were sorted as：Fusarium moniliforme + phloridzin > Fusarium moniliforme > phloridzin > replanted soil control. Three treatments inhibited the growth of bacteria in the replanted soil，promoted the growth of fungi and changed the community structure of soil fungi. The activities of soil catalase，soil urease，soil invertase，soil neutral phosphatase were significantly reduced with the three treatments；In August，soil urease was reduced by 14.8%，29.1%，53.4% compared with the replanted soil control. In conclusion，Fusarium moniliforme and phloridzin alone or in combination significantly inhibited the growth of M. hupehensis Rehd. seedlings，Fusarium moniliforme and phloridzin treatment was the most significant. These results suggested that the combination of phloridzin and Fusarium moniliforme could increase the phenomenon of apple replant disease.

Key words: apple, replant disease, phloridzin, Fusarium moniliforme