The heavy metal lead (Pb) pollution in water impacts human health and the water ecological environment. In order to realize the on-site and rapid detection of heavy metal Pb in water, in this paper, Chlorella pyrenoidosa was used as the adsorbent, and the rapid detection of heavy metal Pb in water based on enrichment by Chlorella pyrenoidosa combined with X-ray fluorescence (XRF) spectroscopy was carried out. The results show that when the pH value of the reaction solution of Chlorella pyrenoidosa and heavy metal Pb was 7. The reaction temperature was 25 ℃, Chlorella pyrenoidosa had the fast and high-efficient adsorption characteristics to heavy metal Pb, when the reaction time was 5 min, the adsorption efficiency of heavymetal Pb in the wide concentration range of 0.012 8～0.353 5 mg·L-1 was as high as 92%, but the adsorption efficiency of metalloid As was lower than 5%. Therefore, the enrichment based on Chlorella pyrenoidosa could effectively avoid the interference and influence of the optimal Kα characteristic peak of As on the optimal Lα characteristic peak of Pb in the XRF measurement process when the heavy metal Pb and metalloid As coexist; Under the optimal adsorption reaction conditions of Chlorella pyrenoidosa for heavy metal Pb, when the enrichment volume of the reaction solution was 10 mL, a quantitative detection method of heavy metal Pb in water based on the combination of Chlorella pyrenoidosa enrichment and XRF spectroscopy was established. There was a good linear relationship between the concentration of heavy metal Pb in water and the net integrated fluorescence intensity of the Lα characteristic peak of Pb in the XRF spectrum with a correlation coefficient r of 0.990. The detection limit of the method was 7.2 μg·L-1, which was lower than the standard limit of heavy metal Pb in the Class Ⅰ water quality standard in “Environmental Quality Standard for Surface Water (GB 3838—2002)” of China. This method was adopted to detect the heavy metal Pb in the actual water samples of Paihe, Kuanghe, Nanfeihe, Silihe and Shiwulihe in Hefei City, and the recoveries were all within the range of 87.84% to 115.66%, indicating that the established rapid detection method of heavy metal Pb in water which combined with enrichment by algal cells and XRF spectroscopy could be well applied to the rapid analysis and detection of heavy metal Pb in actual water. This research will provide a method basis for developing on-site and rapid monitoring techniques and instruments for heavy metals in water.