In this paper, the method of PicoTagTM amino acid analysis was introduced to measure the level of L-arginine in aortic wall of rabbits. Firstly, the sample (isolated artergal ring of rabbits) was extracted with trichloroacetic acid and water-saturated ether. The crude product was further assayed by PicoTagTM amino acid analysis. The peak area of L-arginine's was corrected by 991 purity analysis disk, the L-arginine levelwas determined by comparing with standrad L-arginine peak area. Three groups of samples was assayed. The statistical L-arginine level of the three group is valuable.