【Aim】Serratia marcescens AHPC29, which was isolated from the pupa chamber of Monochamus alternatus, a vector of the pinewood nematode, has been shown to be pathogenic to the pinewood nematode. The pinewood nematode, Bursaphelenchus xylophilus, is an important invasive forest pest that can cause pine wilt disease. This study was carried out to investigate the effect of S. marcescens AHPC29 on pine wilt disease under conditions of increasing strain in a laboratory setting. 【Method】 The effects of S. marcescens AHPC29 on pine wilt disease were analyzed by irrigating bacteria cultures into pine trees that had been artificially infected with pinewood nematodes in a greenhouse. The effects of culture medium components and culture conditions on the growth of S. marcescens AHPC29 were determined by single-component screening and orthogonal experiments to explore the optimal conditions for the growth of S. marcescens AHPC29. 【Result】 For the pines infected with pinewood nematodes, the growth status of the treatment group irrigated with the AHPC29 strain was better than that of the control group, and the pinewood nematode content in the trees was significantly reduced. The optimal medium composition was 0.1% lactose, 0.5% complex amino acids, 0.5% KNO₃, and 1.5% MgSO₄, among which the most influential component was the nitrogen source. The optimal inoculation ratio was 7%, the optimal filling ratio was 40%, the optimal rotate speed was 180 r·min^-1, the optimal temperature was 30 ℃, and the optimal culture time was 36 h. 【Conclusion】 In this study, the optimal conditions for the growth of S. marcescens AHPC29 were obtained, and it was confirmed that the strain had good application potential in the control of pine wilt disease, which provided a theoretical basis for its application as a biocontrol bacterium.