Abstract: This paper reports a comparative study on the morphological and histological characters of Chinese crude drugs Huang Qi(Radix Astragali )derived from the dried roots of AStragalus membranaceus(Fisch.)Bge.var.mongholicus( Bge. ) Hsiao,A. membranaceus(Fisch.)Bge.,A. floridus Benth.A. tongolensis Ulbr.and A. chrysopterus Bge.. A detailed scanner electronic microscope(SEM)observation on the roots was carried out for the first time. It was found that there are some new anatomical characteristics of species variations:1)The pitaperture in reticulate vessels of A.floridus is often long-narrow shaped and is almost as long as the diameter of the vessel,which may be referred to linear pit.2)The vestured pits are quite different in A.membranaceus and A. membranaceus var.mongholicus a narrow gap among the grain-like excrescences in the center of the pit cavity being shown in the former but not in the latter.For comparative study in longitudinal sections, some measurable parameters have been designed,such as(1)the distance between cambium and the ring of phloem fibers near the cambium,2)the radial length of the region of phloem fiber bundles near the cambium and(3)the height width andshape of the xylem medullary ray.