Abstract: High temperature composting and vermicomposting are both the main means of value-added and resource utilization of agricultural waste. Due to the fact that the final product of vermicomposting, vermicompost, and the growth and reproduction of earthworms during the composting process mainly depend on the physical and chemical properties of the substrate, high-temperature composting is often used as a pretreatment method for vermicomposting to improve the palatability and conversion rate of the substrate. Biochar, with its well-developed porous structure and abundant surface functional groups, has become an important exogenous additive for reducing nutrient loss and promoting compost maturity. Furthermore, biochar can provide colonization sites for microorganisms in the intestines of earthworms, further facilitating the earthworms' absorption of nutrients from the substrate.In order to reduce nutrient loss during the high temperature composting and vermicomposting processes, improve the conversion rate of base materials, and promote the weight gain and reproduction of earthworms, this study added different proportions of biochar (0, 5%, 10%) to chicken manure and corn stover for composting. Eisenia fetida was used as the base material for 35 days of vermicomposting, and the total nutrients, available nutrients, trace elements, humus components, and growth and reproduction of high temperature composting and vermicompost were analyzed. Scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), and three-dimensional fluorescence spectroscopy (EEM) were used to analyze the pre-composting and vermicompost. Characterize the microstructure, elemental composition, and functional groups of feces. The results showed that after earthworm transformation, the large particles on the substrate surface are converted into tightly connected small granular substances, and obvious pores appear. However, the addition of biochar treatment reduces the surface area and total pore volume, while increasing the average pore diameter. The addition of biochar increased the pH value and conductivity of High temperature composting, while promoting the humification of the base material and increasing the content of abundant and trace nutrients. Compared with High temperature composting, the total nutrients, humus, ammonium nitrogen, available phosphorus, and available potassium content of each treatment decreased after vermicomposting, while the nitrate nitrogen content increased. Humic acid was further converted to fulvic acid. FTIP, XRD, and EEM indicate that Biochar was added to promote the degradation of aromatic compounds and lignin in earthworm compost, and the increase of polysaccharides. In addition, the total eartnworm biomass, mass of single adult earthworm, survival rate and cocoons of earthworms treated with biochar were significantly (P < 0.05) higher than those of the control group (CCM0), and beneficial for the retention of nutrients in vermicompost. Among them, the total content of alkali hydrolyzed nitrogen, available phosphorus, and available potassium in vermicompost treated with 5% biochar (CCM1) and 10% biochar (CCM2) increased by 12.81% and 143.56% respectively compared to the control group (CCM0). Therefore, in the combined treatment of high temperature composting and vermicomposting, the addition of biochar increased the nutrients after composting, while effectively reducing the nutrient loss after vermicomposting, providing a new approach for the weight gain and reproduction of earthworms and the production of high-quality vermicompost.