Objective: To study collagen distribution and its quantitative variation in t he aortic adventitia of spontaneously hypertensive rats Methods: Sirus red stain was used to observe collagen distribution in aortic adventitia；Chloramine-T oxidation assay was employed to quantitate the collagen of aortic adventitia；Immuno-histochemical staining was adopted to detect type Ⅰ、Ⅲ collagen synthetic characteristic of vascular adventitial fibroblasts. Results: Collagen of rat aoritc wall mainly distributes in adventitia；SHR shows more collagen deposition in adventitia than WKY at the age of 8weeks and 24 weeks；The immuno-histochemical staining of type Ⅰ、Ⅲ collagen in vascular a dventitial fibroblasts is positive. Conclusions: All those results indicate that vascular adventitia ma y be involved in hypertensive vascular remodeling.and vascular adventitial fibroblasts can synthe size collagen type Ⅰ and Ⅲ.