Abstract:L-citrulline in the lateral bud of saffron was quantitatively analyzed for the first time and the extraction method was optimized. After ultrasonic extraction, the samples were derived with 2,4-dinitrofluorobenzene (FDNB) and analyzed by Ultra High Performance Liquid Chromatography. The results showed that a good linear relationship was obtained for L-citrulline in the concentration range of 0.98~62.50 μg/mL with R2 = 0.9998,the detection limit of L-citrulline was 0.2440ng/mL(S/N=3), and the average recovery was 101.15% ( n=6, RSD=1.00% ). After the extraction method was optimized,the content of L-citrulline in the lateral bud of saffron was determined to be about 26.69 mg/g.