Intis study soils with different mirex concentrations (0-27mg/kg) were collected to set up earthworm inoculation trials. High-throughput sequencing was used to analyze the structure and function of earthworm intestinal and soil indigenous microbial communities. Meanwhile, the keystone microbial taxa were identified through network analysis. The results obtained here found that 1) The structure and composition of the earthworm intestinal bacteria varied more significantly than those of the soil indigenous bacteria (P<0.05); 2) The keystone bacteria remained stable in the worm gut and the soil despite varying mirex concentration, which was mainly consisted of Aeromonas, Flavobacterium, Gallerella, Microvirga, Pedobacter, Ramlibacter, Zavarzinella; 3) The keystone bacteria had higher network connectivity than the rest bacteria, whose mean degree centrality, closeness centrality, eigenvector centrality values were 136.7, 0.44 and 0.52, respectively, clearly higher than those in the rest bacteria (91.52, 0.42 and 0.33, respectively). In addition, the keystone bacteria were closely involved in the carbon/nitrogen transformation and pesticide degradation, which not only protect the keystone bacteria from mirex toxicity, but might also assist other bacteria in relieving pesticide toxicity. The results obtained here shed novel light on understanding the mechanism of the earthworm intestinal and the soil indigenous bacteria in counteracting OCP stress and sustaining the homeostasis of microbial communities in the soil.