OBJECTIVE：To establish the method for content determination of 17 kinds of amino acids in Sargassum and its adulterants，and to carry out cluster analysis ，so as to provide reference for quality control of Sargassum. METHODS ：Totally of 18 batches of sample （S1-S6 as certified product ，S7-S18 as adulterants ）were collected. After acid hydrolysis ，amino acids contents were detected by using automatic amino acid analyzer. The separation was performed on LCAK 06/Na sulfonic acid cation exchange resin column with mobile phase consisted of buffer-regeneration system （gradient elution ）at the flow rate of 0.45 mL/min （elution pump ）and 0.25 mL/min（derivative pump ）. The detection wavelengths were set at 440 nm（proline）and 570 nm（other amino acids ），and the sample size volume was 50 μL. PASW Statistics 18.0 software was used ，and cluster analysis was conducted by using group connection method of cluster analysis with “square Euclidean distance ”as the measurement standard. RESULTS ：17 kinds of amino acids were well separated without interference from blank sample. The linear relationship between mass concentration and peak area was good （all r were over 0.998），and the upper and lower limits of the linear range were 48.06 μg/L （cystine）and 1.501 μg/L（glycine），respectively；RSDs of precision ，reproducibility and stability tests were lower than 2％. The average recoveries were between 90.60％-101.56％（RSDs were 0.88％-2.15％，n＝6）. 17 kinds of amino acids were detected in Sargassum and its adulterants ，among which the contents of glutamic acid ，aspartic acid ，leucine，alanine，glycine and valine were relatively high . Results of cluster analysis showed that 18 batches of sample were clustered into 4 categories，i.e. S 1-S6 into one category；S7-S9 into one category ；S10-S12，S16-S18 into one category ；S13-S15 into one category ；which was consistent with the identification result of Sargassum and its adulterants . CONCLUSIONS ：The method is simple ， rapid， accurate and reproducible，and can be used for the quantitative analysis and identification of amino acids in Sargassum and adulterants.