Morphological and anatomical features were observed during the formation of adventitious roots of sea buckthorn by microcuttage multiplication with paraffin method. The results showed that adventitious root primordium originated from two areas(one was cell of vascular cambium, and the other was cell from cortex parenchyma) was inductive root formation type. When the adventitious root of sea buckthorn continued to grow, this phenomenon that one of its part extended out in ray direction and the other part would connect with the marrow of stem while it was stretching out remained undiscovered in other species. In general, formation of adventitious root of sea buckthorn can be divided into four stages: 1)The cells of cortex parenchyma and vascular cambium divided into parenchyma cell groups which contained the characteristics of meristem, stood in a line and bore dense cytoplasm concentration.2)Newly formed parenchyma cell groups kept dividing and dedifferentiating, forming adventitious root primordium initial cells which showed strong mitogenetic ability. 3)Root primordium initial cells continued to divide and extended in ray direction which was far from axis. Then the root primordium formed. 4)What’s more, root primodium pierced through phloem ray and cortex and kept stretching out to the lenticel direction, then the adventitious root formed. Not until adventitious root inner vascular system well matured and connected with stem vascular system, would it stretch from lenticel.