FTIR spectra of fourth-generation space bred radix isatidis and FTIR spectra of radix isatidis in a ground group were determined on the whole. Comparative analysis was conducted on main constituents (components) to accumulate data for comprehensively understanding and thoroughly studying the inherent property, and to explore a method of evaluating the quality of space bred radix isatidis. The results showed that slight difference existed in the positions and shapes of the absorption peaks in FTIR spectra of samples between the two groups. The intensities of main absorption peaks of radix isatidis in the space group were strengthened to various degrees compared with those in the ground group .The absorption peaks were markedly enhanced at wave numbers of 1 047, 1 630 and 1 412 cm-1, indicating that the contents of polysaccharides, sterides, triterpenes and flavanoids, particularly polysaccharides with anti-viral efficacy, increased to different extents. The absorption peak intensity of space radix isatidis at the wave number of 1 745 cm-1 was weakened compared with that of radix isatidis in the ground group, suggesting the reduction of glycosides and organic acids. It is concluded that the contents of a plurality of active components of radix isatidis in the space group are elevated. New radix isatidis varieties with high contents of diverse active components can be harvested by spaceflight mutation breeding.