Abstract: Identifying novel therapeutic efficacies of traditional Chinese medicine (TCM) and their underlying mechanisms is essential for TCM modernization and development. Apocynum venetum leaf (AVL) is used both as an antihypertensive medicine and as a food. Whether AVL extract possesses additional therapeutic efficacies remains to be investigated. Here, we examined the potential effect of AVL extract on ameliorating postmenopausal osteoporosis (PMO) and identified the effective fractions and underlying mechanisms of its efficacy. We found that the total extract of AVL substantially relieved osteoporosis symptoms in both mouse and rat ovariectomized models. Moreover, the AVL-95% fraction, accounting for only ~2% of the total extract, exhibited a therapeutic effect on osteoporosis comparable to that of the total extract. Notably, the AVL-95% fraction improved both cancellous and cortical bones. Additionally, it exerted beneficial effects on both femurs and vertebrae in ovariectomized (OVX) mice. Mechanistic studies showed that AVL-95% inhibited osteoclastogenesis by suppressing RANKL signaling. Importantly, AVL-95% did not exhibit apparent toxicity in acute and chronic toxicity evaluations. Collectively, our work reveals a previously unknown efficacy of AVL in PMO intervention and an underlying mechanism of this efficacy, highlighting the anti-PMO application potential of AVL.