Abstract: A simple method for the determination of benz(a)pyrene in groundwater by ultra performance liquid chromatography was developed. The method was discussed for the wavelength of fluorescence absorbance detection and the temperature of chromatographic column. The separation was carried out on Acquity C₁₈ column with methanol as the mobile phase at a constant flow rate of 0.40 mL/min. Linear detection response was obtained for concentrations ranging from 0.082 to 200 ng/mL.The limit of detection was 0.033 ng/mL. The retention time of benz(a)pyrene is 0.61 min. The ultra performance liquid chromatography and high performance liquid chromatography method was compared to detect the benz(a)pyrene in this paper. This technology, ultra performance liquid chromatography, has significant theoretical advantages in speed, resolution, and sensitivity of analysis, especially time saving and solvent consumption.