Abstract: A new type of composite adsorbent SBC-3, which is used to adsorb nitrogen and phosphorus pollutants in water, was developed by pyrolysis of waste rice husks at high temperature, and then combined with iron modification and attapulgite. Through a series of adsorption experiments, the effects of different pH values, reaction time and initial concentration on the adsorption capacity of nitrogen and phosphorus were studied. The results showed that SBC-3 had a high adsorption capacity of nitrogen and phosphorus, and the adsorption capacity of phosphorus and nitrogen could reach 11.384 mg/g and 29.452 mg/ g under optimal conditions. Compared with rice husk carbon (SBC-1) or single iron modified rice husk carbon (SBC-2), SBC- 3 showed more irregular pore structure and higher adsorption capacity, especially for nitrogen and phosphorus. In addition, competing cations (such as Ca²⁺, Mg²⁺) had a negative effect on the adsorption of ammonia nitrogen, while the adsorption of phosphate was almost undisturbed. The actual pot experiment showed that the growth height, elongation and germination rate of water spinach could be significantly increased by applying biochar after adsorbed N and P. The results of the actual sewage treatment experiment showed that the removal rates of ammonia nitrogen and phosphate of SBC-3 in the fifth sewage treatment plant of Xi’an could reach 92.3% and 42.3%, respectively, which indicates that SBC-3 has a good prospect in practical application.