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燕麦镰刀菌(Fusarium avenaceum)是引起燕麦(Avena sativa)根腐病的主要病原菌之一，为开发高效防治燕麦根腐病的绿色生物菌剂，本研究从健康燕麦根际土壤中分离筛选出一株燕麦镰孢菌高效拮抗细菌YF，并开展了形态学和分子鉴定，研究了该菌的抑菌谱及对燕麦镰孢菌的室内防治试验和作用机理。结果表明，该菌被鉴定为多粘类芽孢杆菌(Paenibacillus polymyxa)。活性测定发现该菌对燕麦镰刀菌的菌丝生长抑制率达到70.69%，对孢子萌发抑制率为85.92%。通过抑菌谱筛选发现该菌对常见的8种病原真菌均有较好的防治作用。利用该菌发酵液处理后燕麦镰孢菌菌丝出现异常分枝、囊泡状畸形且伴有细胞壁破裂。盆栽试验表明，该菌对燕麦根腐病的防治效果达到81.45%，其防效显著高于化学农药多菌灵(61.87%) (P < 0.05)，且该菌对燕麦表现出较好的促生长作用。因此，该菌株多粘类芽孢杆菌具备了开发燕麦根腐病生物防治菌剂的潜力。“,”Fusarium avenaceum is one of the main pathogens causing root rot in oats (Avena sativa). In order to develop a green biological inoculant for effective prevention and control of oat root rot, we isolated from healthy oatmeal rhizosphere soil F. avenaceum, an efficient oat antagonist bacteria YF, carried out morphological and molecular identification of the antibacterial spectrum of this bacterium, and investigated through an indoor control test the mechanism of this bacterium against F. avenaceum. The strain was identified as Paenibacillus polymyxa. The activity test showed that the strain had an inhibition rate of 70.69% against the mycelial growth of F. avenaceum and 85.92% against spore germination. Through bacteriostatic spectrum screening, it was found that this strain is effective in controlling eight common pathogenic fungi. The mycelia of F. avenaceum treated with the fermentation broth showed abnormal branching, vesicular deformities, and rupture of the cell wall. In the potted experiment, the control effect of this strain on oat root rot reached 81.45%, which was significantly higher than that of carbendazim (61.87%) (P < 0.05). In addition, this strain showed a better growth promoting effect on oat plant. Therefore, this strain of P. polymyxa has potential as a biological control agent against oat root rot.