Objective To explore the therapeutic effects of two different doses of Buyang Huanwu decoction containing Astragalus on erectile dysfunction (ED) in rats with cavernous nerve injury. Methods Thirty-two Sprague- Dawley ( SD) rats were randomly divided into four groups: sham operation model, 30 g ( model + Buyang Huanwu decoction containing 30 g Astragalus) and 120 g (model + Buyang Huanwu decoction containing 120 g Astragalus). The cavernous nerve of the rats was surgically clamped (but not cut) to establish the rat model of ED caused by cavernous nerve injury. Five days after the operation, a 30 g or 120 g dose of Astragalus was used for the gavage intervention of Buyang Huanwu decoction, or the same volume of normal saline ( sham and model groups) was given, once a day for 30 consecutive days. After 30 days, the intracavernous pressure ( ICP) of the rat corpus cavernosum was measured. Masson staining was used to observe the content of smooth muscle and collagen deposition in the spongy tissue. Fluorescence and western blotting were used to detect changes in neuronal nitric oxide synthase ( nNOS), neurofilament light polypeptide (NF-L), growth associated protein 43 (GAP-43) expression in each group. Results Compared with the sham group, the model group showed significantly decreased ICP ( P < 0. 01), decreased area of penile smooth muscle / collagen ( P < 0. 01), and significantly decreased levels of NF-L, nNOS and GAP43 (P< 0. 01). Compared with the model group, the rats in the 30 g and 120 g Astragalus groups showed significantly increased ICP (P < 0. 01), increased area of penile smooth muscle / collagen (P< 0. 01), and significantly increased levels of nNOS, NF-L and GAP43 (P< 0. 01). Compared with the 30 g group, the rats in the 120 g Astragalus group showed significantly increased ICP (P< 0. 05), increased area of penile smooth muscle / collagen (P< 0. 05), and significantly increased levels of nNOS, NF-L and GAP43 (P< 0. 01). Conclusions Buyang Huanwu decoction containing Astragalus obviously improved ED in cavernous nerve injury model rats. The higher dose of Astragalus (120 g), which is used in the original prescription of “Medical Forest Correction”, was more efficacious.