Abstract: HPLC was applied to the determination of 18 amino acids in cortex lycii. The sample of cortex lycii was derived with 10-ethyl-acridine-2-sulfonyl chloride as precolumn derivatization reagent. Akasil-C18 chromatographic column was used as stationary phase with mixtures of acetonitile (5+95) solution and acetonitile (95+5) solution with different mixing ratios as mobile phase in the gradient elution, and determined with fluorescence detector. Linearity ranges of the 18 amino acides were found in the same range of 32 fmol-100 pmol with detection limits (3S/N) in the range of 2.06-8.65 fmol. Values of recovery found by standard addition method were in the range of 96.4%-107%, and values of RSD′s (n=6) less than 4.0%.