Object To study systematically the constituents in peel of Citrus L and Poncirus Raf both growing in China and in Korea and find out some differences among them by comparison with their Results Methods The powdered plant materials were extracted by water steam distillation to give essential oils, which were analyzed on GS MS and elucidated on the standard MS data, their relative contents in percentage were calculated by area normalization And then, the qualitative and quantitative analysis of the