Abstract: Objective To establish a fast method for detecting arsenic in urine by atomic fluorescence spectrometry. Methods Samples were treated with nitric acid and hydrogen peroxide and digested in a microwave digester, the volume was adjusted directly with deionized water without dispelling acid. The concentration of arsenic in urine was detected by atomic fluorescence spectrometry under optimal conditions. Results The improved procedure for sample pretreatment could accelerate the measurement of arsenic in urine; the lowest detection limit was 0.101 μg/L, the recovery was 94.8%~101.6%, and the relative standard deviation was 1.94%. Conclusions The result obtained by this method was accurate, less time-consuming, digested with less acid, and easy to operate. It could be used as an effective method for detecting arsenic in human urine.