Abstract: Notoginseng (Sanqi), the root of Panax notoginseng (Burk.) F. H. Chen (Araliaceae), is one of the most valuable traditional Chinese medicines (TCM). It has been widely used in China with a long history for treatment of haemorrhage, edema, and cardiovascular disorders. Steamed P. notoginseng has been considered to have stronger therapeutic functions than raw P. notoginseng in the treatment of tumors, cardiovascular diseases, etc. Saponins are the principal chemical and pharmacological constituents in P. notoginseng. Thus, it is of great importance to determine the constituent saponins and determine any differences between fresh P. notoginseng and steamed P. notoginseng. We used a rapid and direct analytical method based on liquid extraction surface analysis combined with mass spectrometry (LESA-MS) to identify saponins in the xylem, phloem and cambium of fresh and steamed P. notoginseng root slices. The results revealed that ginsenosides Rg1, Rb1, Re, Rd, notoginsenoside R1 and their malonyl group versions were most abundant in fresh root slices, while in steamed slices ginsenosides Rg5, Rk1 and other minor polar components could be detected, and the relative content of large polar components was lower. The described method is fast, robust and sensitive and the process does not need traditional and cumbersome pretreatment such as crushing, extraction and separation. It is the first non-destructive study on the differences in saponins between fresh and steamed P. notoginseng root slices.