Nano B2O3/TiO2 composite as a new sorbent was synthesized， and the characteristic of the synthesized material was studied by scanning electron microscope（SEM） and infrared spectrometry （IR）. By investigating the optimal conditions of adsorption and desorption of nano B2O3/TiO2 composite for Ag+， a new method for the determination of trace silver was proposed. After oscillated for 20 minutes at 22 ℃ and pH 4.3， silver could be quantitatively adsorbed by nano B2O3/TiO2 composite， and the adsorption capacity was obtained to be 11.72 mg/g. The adsorbed silver could be eluted from the surface of the absorbent with 0.1 mol/L HNO3-0.05 mol/L thiourea（1∶4）. Under the optimum experimental conditions， the calibration curve was linear over Ag+ concentration in the range of 0.01-4.00 mg/L， with a detection limit（3σ） of 2.01 μg/L.The RSD（n=11） for determination of 0.4 mg/L Ag+ was 1.8%. The spiked recoveries ranged from 95% to 105%. The method was applied in the determination of trace silver in slag samples with satisfactory results.