Typical sections of north Grand Canal in Beijing (Tugou, Yulin Village and Hehe Station) were selected, and the upper 0-60 cm sediments were collected to operate batch equilibrium static experiment on adsorption and desorption of nitrogen or phosphorus. Adsorption/desorption dynamic characteristic analysis was developed combing the experiment result and several dynamics models. Based on that, we aimed to provide a suitable dynamics model to describe the adsorption/desorption dynamic characteristic of sediments on nitrogen and phosphorus in the north Grand Canal, as well as figure out the influence aspects of the model parameters. The research showed that:1) Three typical stages, which were quick reaction stage, slow reaction stage and equilibrium stage, were obviously showed in adsorption and desorption curves of nitrogen or phosphorus on sediments in the north Grand Canal; 60% of the total adsorption and desorption amount occurred in the first stage (0-0.5 h), and the adsorption rate is higher than the desorption rate. 2) equilibrium adsorption/desorption quantity of every typical sections in the north Grand Canal were difference, the order of equilibrium adsorption quantity is:S_{(Yulin Village)} > S_(Tugou) > S_{(Hehe Station)}, the order of equilibrium adsorption quantity for ammonia nitrogen is:S_(Tugou) > S_{(Yulin Village)} > S_{(Hehe Station)}, for phosphate:S_{(Hehe Station)} > S_(Tugou) > S_{(Yulin Village)}; and chemical adsorption was the main interaction; with the depth increasing, the adsorption rate and desorption rate were decreased, and the upper 0-20 cm has a higher adsorption ability. 3) Lagergren second-order kinetic model performed the best fitting result with the experiment data, and the regression equations are k₂=S_max^-0.369+0.163;q_e=0.022 S_max+18.077 K_f+41.947. Through the simulation solution, we obtained that there would be 6%-42% of phosphate and 52%-80% of nitrogen detaching from the sediments by desorption process at 400 mg/L nitrogen and phosphate concentrations, which will probably cause recontamination to the overlying water and pollution risk to ground water through river water percolation.