A composite adsorbent (CS-PAC) was prepared using chitosan (CS) and powdered activated carbon (PAC) for the adsorption of dissolved organic matter (DOM) in the secondary effluent of a sewage plant, with UV254 as the DOM The detection parameters of the concentration were used to study the adsorption performance and kinetic characteristics of the composite adsorbent on DOM. The experimental results show that the removal rate of DOM increases with the increase of the adsorbate concentration. With the increase of the dosage of the composite adsorbent and the extension of the contact time, it first increases and then tends to be stable. The adsorption basically reaches equilibrium after 60 min, and the highest removal rate of DOM reached 74.17%. The adsorption kinetics study shows that the adsorption process is more in line with the Freundlich model and is dominated by multi-layer adsorption; the adsorption process of the composite adsorbent to DOM is suitable for the description of second-order kinetics, and the main adsorption is chemical adsorption.