This study investigates the standardization and micromechanistic aspects of tetracycline adsorption by biochar. The research establishes the relationship between carbonization degree and adsorption capacity, constructs a standardized microscopic model for biochar adsorption of tetracycline, and explores potential reaction mechanisms. Results show that the tetracycline adsorption capacity of biochar increases from 16.08 mg L⁻¹ to 98.35 mg L⁻¹ with increasing carbonization degree. Adsorption energy is strongly correlated with the aromatic condensation of biochar (p ≤ 0.01), with a linear relationship (r² ≥ 0.94). For low carbonization degrees, adsorption is primarily driven by chemical bonds (69.21%) and complemented by electrostatic interactions, weak van der Waals forces, or π-π interactions. For high carbonization degrees, hydrogen bonding, van der Waals forces, and π-π interactions determine adsorption (91.1%). Larger carbon clusters result in stronger and more stable adsorption interactions. Carboxyl-functionalized highly carbonized biochar exhibits the highest reaction energy of -1.8370 eV for tetracycline adsorption through electrostatic interactions. The study highlights that high aromatic condensation in the carbon structure of biochar is crucial for efficient tetracycline adsorption. The findings suggest that biochar with higher aromatic condensation levels is more effective for tetracycline removal. The study also identifies the key structural factors influencing tetracycline adsorption by biochar and proposes a standardized model for biochar adsorption. The results provide insights into the development of more cost-effective and efficient biochar adsorption materials.This study investigates the standardization and micromechanistic aspects of tetracycline adsorption by biochar. The research establishes the relationship between carbonization degree and adsorption capacity, constructs a standardized microscopic model for biochar adsorption of tetracycline, and explores potential reaction mechanisms. Results show that the tetracycline adsorption capacity of biochar increases from 16.08 mg L⁻¹ to 98.35 mg L⁻¹ with increasing carbonization degree. Adsorption energy is strongly correlated with the aromatic condensation of biochar (p ≤ 0.01), with a linear relationship (r² ≥ 0.94). For low carbonization degrees, adsorption is primarily driven by chemical bonds (69.21%) and complemented by electrostatic interactions, weak van der Waals forces, or π-π interactions. For high carbonization degrees, hydrogen bonding, van der Waals forces, and π-π interactions determine adsorption (91.1%). Larger carbon clusters result in stronger and more stable adsorption interactions. Carboxyl-functionalized highly carbonized biochar exhibits the highest reaction energy of -1.8370 eV for tetracycline adsorption through electrostatic interactions. The study highlights that high aromatic condensation in the carbon structure of biochar is crucial for efficient tetracycline adsorption. The findings suggest that biochar with higher aromatic condensation levels is more effective for tetracycline removal. The study also identifies the key structural factors influencing tetracycline adsorption by biochar and proposes a standardized model for biochar adsorption. The results provide insights into the development of more cost-effective and efficient biochar adsorption materials.