Four new flavonoids, astragaisoflavans A–D (1–4), along with thirteen known ones (5–17) were isolated from the aerial parts of Astragalus hoantchy. Their structures were established by the extensive spectroscopic analyses including one- and two-dimensional NMR, HRESIMS, IR, and UV results. The absolute configurations of 1–4were deduced based on circular dichroism. Compounds 1–3all possessed a rare modified A-ring and compound 4was a dimeric isoflavan. Compound 5was first identified from genus Astragalusand 6–17were found from A. hoantchyfor the first time. Compound 1and 4were evaluated for their antifungal activity against Alternaria solani(a phytopathogenic fungus), with the result that 1failed to exhibit significant antifungal activity at the testing concentration of 100 μg/mL and the IC₅₀value of 4 was 173.3 μg/mL.