【Aim】Elucidate the effect of Heterorhabditis bacteriophora H06 strain treatment on the hemolymph immune system of Rhynchophorus ferrugineus. 【Method】 The pathogenicity of the H. bacteriophora H06 strain on R. ferrugineus at different stages and its regulation of various indexes of hemolymph were studied through laboratory bioassay and physio-biochemical determination methods. 【Result】 The virulence of the H. bacteriophora H06 strain showed a positive correlation with treatment concentration and treatment time on different stages of R. ferrugineus. After treatment with the H. bacteriophora H06 strain, the total hemolymph and hemolymph esterase levels of R. ferrugineus increased in the early stage and decreased later. The total hemolymph content and esterase activity decreased by 39.73% and 53.36%, respectively, 72 h after treatment compared with the control. The hemolymph protein content decreased, with a short increase at 60 h, and then decreased rapidly. The hemolymph protein content decreased by 74.96% 72 h after treatment. 【Conclusion】 The infestation of the H. bacteriophora H06 strain destroyed the hemolymph immune system of R. ferrugineus. The results may provide a theoretical basis for revealing the pathogenic mechanism of the entomopathogenic nematode to R. ferrugineus.