Plasma aldosterone/renin ratio (ARR) is a useful method for primary aldosteronism (PA) screening. However some confounders, such as medications and dietary, affect plasma renin and aldosterone levels, resulting in false-negative or -positive plasma ARR. This study investigated the association between postmenopausal osteoporosis (PMO) and plasma ARR. Bone mineral density (BMD) was measured by dual-energy X-ray-absorptiometry (DXA) in 324 normotensive postmenopausal women. Based on clinical characteristics and BMD, 186 and 96 subjects were diagnosed as PMO and osteopenia respectively, and the remaining 42 subjects were grouped as normal BMD. Plasma aldosterone concentration (PAC), plasma renin concentration (PRC), parathyroid hormone (PTH), bone alkaline phosphatase (BALP) and 25-Hydroxyvitamin D(25-(OH)D) were determined. Subjects with PMO showed significantly higher levels of PAC (121.0 ± 78.8 vs. 81.8 ± 71.5 pg/ml, p < 0.01 and 121.0 ± 78.8 vs. 91.7 ± 56.2 pg/ml, p < 0.01) and ARR (32.0 ± 53.6 vs. 9.0 ± 9.3 pg/μU, p < 0.01 and 32.0 ± 53.6 vs. 16.3 ± 32.1 pg/μU, p < 0.01) compared to women with normal BMD and osteopenia, respectively. Using ARR ≥ 37.0 pg/μU as the cutoff for positive screening, more false-positive was found in the PMO group when compared to the normal BMD group (24 vs. 2%) and osteopenia group (24 vs. 7%), respectively. PAC was negatively associated with lumbar spine BMD T-score (r = -0.239, p < 0.001), femur neck BMD T-score (r = -0.234, p < 0.001) and total hip BMD T-score (r = -0.228, p < 0.001). PTH was positively associated with PAC (r = 0.119, p < 0.05) and ARR (r = 0.136, p < 0.05). PAC and ARR are elevated in women with PMO, which might increase the risk of false-positive for case detection of PA.