A novel starch ester was prepared by the reaction of starch and 3,5-dinitrobenzoyl chloride (DNBZ-Cl). The product (starch 3,5-dinitrobenzoate, DNBZ-ST) was characterized by means of elemental analysis, Fourier Transform Infrared (FTIR) and 13C NMR spectroscopy. The influences of molar ratio of DNBZ-Cl to anhydroglucose (AGU), reaction temperature and time, and amount of pyridine on the degree of substitution (DS) were studied. The esterification reaction is essentially complete after 2h. Increase in the molar ratio of DNBZ-Cl to AGU leads to an increase in DS when the former varies from 2:1 to 5:1. DS increases with the reaction temperature when the latter is varied from 70 to 100 ℃. DS first increases and then decreases with amount of pyridine, the highest DS was obtained when V(pyridine)/m(starch) was 53mL/g. The thermal stability of DNBZ-ST increases when the DS increases, and the degradation starts at 353℃ for the sample of DS 2.14. Creatinine is a toxin accumulated in the blood of chronic renal failure (CRF) patients and a special adsorbent for creatinine is not reported in literature. DNBZ-ST displayed specific adsorption ability for creatinine, the adsorption equilibrium is reached after 4h. The adsorption capacity increases with the DS of adsorbent and creatinine concentration. When the creatinine concentration is higher than 300mg/L, concentration has no apparent effect on the adsorption capacity. As the temperature of the solution is varied from 19 to 49 ℃, adsorption capacity first decreases and then increases, being lowest at 37℃. The dsorption capacity first increases and then decreases as the pH value increases, and is highest at pH 8.The highest adsorption capacity obtained was 25mg of creatinine per gram of adsorbent at 37℃, pH 7 and a creatinine concentration of 100mg/L. The study on the FTIR and UV-VIS spectra suggested that some chemical reaction took place between the DNBZ-ST and creatinine in buffer solution.