An novel method for synthesis of L-citrulline and L-homocitrulline was reported. In this process, L-ornithine monohydrochloride was reacted with copper Sulfate pentahydrate to protect α-NH2, and δ-NH2 was carbamylated with carbamide, then copper ion was removed through combination with oxalate dihydrate to give L-citrulline with an overall yield of 49.5 %. L-homocitrulline was prepared from L-lysine monohydrochloride in the same method with an overall yield of 53.5%. The structure of aimed compound was confirmed by IR, melting point and optical rotation. This synthetic route was convenient, safe, economical, and environmental friendly.