Abstract: 【Objective】The objective was to explore the influence of walnut leaf litter decomposition on tobacco soil environment, and to clarify the allelopathy of walnut leaf litter on tobacco soil, so as to provide reference for the optimization and adjustment of walnut-flue-cured tobacco composite planting system.【Method】A pot experiment was conducted to study the effects of five walnut litter treatments(CK:0 g/pot, T1:30 g/pot, T2:60 g/pot, T3:90 g/pot, T4:120 g/pot) on the soil of flue-cured tobacco K326.The soil physical and chemical properties, enzyme activities and bacterial diversity of rhizosphere soil under different treatments and transplanting periods were measured, and the effects of different amounts of walnut litter and different decomposition time on soil environment were studied.【Result】With the increase of applied amount of walnut litter leaves, the average soil nitrate nitrogen and ammonium nitrogen content in all transplanting periods continued to increase, both of them reached the peak value(21.19 and 7.64 mg/kg) in T4 treatment, while the soil available potassium(198.88 mg/kg) and organic matter content(13.73 mg/kg) in T3 treatment were the highest.Available phosphorus content and soil pH continued to decrease, the activities of soil sucrase and acid phosphatase increased gradually, while the activities of soil urease and catalase increased first and then decreased in the middle and late stage of the experiment(90 and 120 d after transplanting), and T3 treatment was the best(0.352 NH₃-N mg/g and 8.40 mL/g).The relative abundance of Proteobacteria which accounted for the largest proportion of soil bacterial community, Pseudomonas, Aeromonas, Serratia and Enhydrobacter Chao 1 index and ACE index increased first and then decreased, with T2 treatment(53.51%) and T1 treatment(0.0220, 0.0182, 0.0120 and 0.0038), T3 treatment(2300 and 2300) were the highest, while Shannon index and Simpson index continued to increase.With the decay time of walnut litter, the contents of soil nitrate nitrogen, available phosphorus, available potassium, organic matter and soil pH in all treatments continued to decrease, while the content of soil ammonium nitrogen continued to increase;the activities of soil urease decreased first and then increased, while the activities of acid phosphatase, sucrase and catalase increased first and then decreased.【Conclusion】90 g/pot of walnut leaf litter can form a better soil environment for tobacco planting.The decomposition of walnut litter will lead to significant changes in the main environmental factors of the soil, which may be closely related to the allelopathic potential of walnut.