Abstract: To explore the adsorption mechanism of bagasse fiber and asphalt, Bruner-Emmet-Teller (BET) specific surface area detection method, basket adsorption test and rod-like thin-layer chromatography with flame ionization were used for detection (TLC-FID), the pore structure characteristics of bagasse fiber before and after modification, the easier adsorption of certain components in asphalt by modified bagasse fiber, and the influence of different modified bagasse fiber content on the adsorption process are studied, and the adsorption mechanism is analyzed by theoretical verification combined with adsorption kinetics model. Results show that the surface area of bagasse fiber increases slightly after modification, and the total pore volume, micropore area and volume increase significantly, reaching 241%, 170% and 276%, respectively. After reaching the adsorption equilibrium, the saturated mass fraction decreases by 5.77%, the aromatic mass fraction increases by 20.75%, the gum mass fraction decrease by 29.37%, and the asphaltene mass fraction decreases by 5.66%. With the increase of the content of modified bagasse fiber, the adsorption rate increases from 15.25% to 34.16% and the unit equilibrium adsorption decreases from 4.827 to 2.162. The quasi-first-order and quasi-second-order adsorption kinetic models were used in the experiment. The quasi-second-order kinetic model has better fitting effect, and the unit equilibrium adsorption quantity q_e (3.247) predicted by the model is closer to the unit equilibrium adsorption quantity q_e (3.098) measured by the experiment. The adsorption process of colloid is from the outside to the inside, the insufficient driving force and the number of adsorption sites allows the adsorption to reach a balance.