Abstract: To evaluate the potential environmental risks of utilizing tobacco waste as a resource, biochar was produced from tobacco waste (including stalk, stem and leaf) at pyrolysis temperatures of 300 ℃, 450 ℃ and 600 ℃. The effects of leachates from different biochars on wheat seeds germination, seedling growth, antioxidant enzyme activities, and their acute ecotoxicity to earthworms (measured by median lethal concentration, LC₅₀, and mortality) were investigated. The results showed that the pH and electrical conductivity (EC) of leachates from stalk-, stem-, and leaf-derived biochars all increased with rising pyrolysis temperature. The heavy metal contents in the leachates varied depending on the feedstock and pyrolysis temperature, generally following the order: stem-derived biochar > leaf-derived biochar > stalk-derived biochar. Leachates from biochar pyrolyzed at 600 ℃ exhibited lower heavy metal concentrations. The inhibition rates of wheat seed germination, shoot length, and root length by leachates from stalk- and leaf-derived biochars intensified with increasing pyrolysis temperature. In contrast, stem-derived biochar leachates exhibited a U-shaped response, where inhibition first decreased and then increased with temperature, peaking at 600 °C. At this temperature, inhibition rates for germination, shoot length, and root length reached 78.00%, 92.07%, and 90.57%, respectively. The activities of catalase (CAT), peroxidase (POD), superoxide dismutase (SOD) and malondialdehyde (MDA) content in wheat seedlings were significantly increased by leachates from stem-derived biochar. The correlation analysis revealed significant relationships between the ecotoxicity of wheat seedlings and factors including pH, EC, and the concentrations of specific heavy metals (Ni, As, and Cu). The earthworm mortality increased with higher concentrations of biochar leachates and exhibited a trend of first increasing and then decreasing or stabilizing with pyrolysis temperatures. The LC₅₀ for earthworms decreased and then stabilized with increasing pyrolysis temperature. Leachates from stem-derived biochar demonstrated the most pronounced acute toxicity to earthworms; at the pyrolysis temperature of 450 ℃ and 600 ℃, the 24-h and 48-h LC₅₀ for earthworms were the lowest, with values of 37.11 g/kg and 12.38 g/kg, respectively. In conclusion, stem-derived biochar leachates exhibited the highest ecotoxicity, which was,modulated by pyrolysis temperature. This study confirms that biochar leachates from tobacco waste possess potential ecological toxicity, the extent of which is closely associated with both the feedstock type and pyrolysis temperature. These findings provide a critical basis for environmental risk assessment in the resource utilization of tobacco waste.