Abstract: This study explored the effects of extreme thermophilic bacteria combined with thermophilic pretreatment on promoting the maturity and quality of livestock manure compost, aiming to provide theoretical and practical bases for further optimizing high-temperature rapid composting technology. 10 strains belonging to Geobacillus and Thermus were used to screen extreme thermophilic bacteria for inoculation in thermophilic pretreatment composting by measuring the activity of thermophilic degrading enzymes and the survival ability under thermophilic pretreatment conditions (85 ℃, 4 h). Three treatments of temperature controlled composting were conducted for 42 days, conventional composting (CK) was set as control, thermophilic pretreatment composting (HPC) and thermophilic pretreatment composting inoculated with extreme thermophilic bacteria (IHPC) as two treatments. The survival rates of Strains E, NN-37, 80-39, NN-68 and 80-61 under thermophilic pretreatment conditions were 98.0%, 64.3%, 60.8%, 58.8% and 55.0%, respectively. Strains NN-37 and NN-68 could detect the activities of thermophilic protease, amylase, xylanase and lipase. Strains 80-39 and 80-61 could detect the activities of thermophilic protease, amylase and xylanase. Strain E could detect the activities of thermophilic protease and xylanase. At the end of composting, the total organic carbon (TOC) content of IHPC (312.65 g·kg^-1) was lower than that of CK and HPC (331.74 and 317.06 g·kg^-1); The total nitrogen (TN) content (18.91 g·kg^-1) increased by 15.16% and 4.30% compared with CK and HPC, respectively; The content of humic acid (HA) (62.62 g·kg^-1) increased by 27.72% and 6.95%, respectively; The germination index (GI) (79.04%) increased by 25.90% and 16.42%, respectively; The H/F (2.13) and HP index (0.68) increased by 52.14%, 22.41% and 17.24%, 7.94%, respectively. TOC had the greatest correlation with compost maturity, which was negatively correlated with HA, H/F, HP and GI, and positively correlated with fulvic acid (FA). Membership function analysis show that the comprehensive effect of IHPC was the best. Extreme thermophilic bacteria combined with thermophilic pretreatment can significantly accelerate composting maturity and enhance the degree of humification in livestock manure composting, which has good application potential.