Primary objective:

To compare the bone mineral density (BMD) change under the treatment of denosumab with eldecalcitol or native vitamin D in postmenopausal women with osteoporosis on bone mineral density.

Secondary objective:

To compare the efficacy of denosumab with eldecalcitol or native vitamin D treatment in postmenopausal women with osteoporosis on bone turnover markers, serum PTH, serum calcium, serum phosphorus, muscle mass, muscle strength, body balance ability, and quality of life.

Inclusion Criteria:

• 1.Postmenopausal patients with osteoporosis, measured by dual energy X-ray absorptiometry (DXA), the T value of lumbar spine, femoral neck or total hip BMD is ≤-2.5, or with low mineral density (-2.5 < T-score < -1.0) plus a fragility fracture of the proximal humerus or distal forearm, or a history of vertebral compression fracture.
• 2.Voluntarily participate in this study and sign the informed consent.

Exclusion Criteria:

• 1.Suffering from hyperthyroidism, Cushing's syndrome, hypogonadism, poorly controlled diabetes mellitus (glycated hemoglobin [HbA1c>9.0%]), or other diseases that may lead to secondary osteoporosis.
• 2.Patients who have received denosumab therapy before screening: received oral bisphosphonate treatment more than 3 years or received bisphosphonate treatment within 6 months before screening, or received treatment with glucocorticoids, vitamin K, active vitamin D compounds, selective estrogen receptor modulators, calcitonin, hormone replacement therapy, or teriparatide within the 8 weeks prior to study enrollment..
• 3.Patients who at screening have urinary tract stones detected on B-mode ultrasonography or who have a prior history of urolithiasis.
• 4.Corrected serum calcium value at screening exceeds 2.6mmol/L (10.4mg/dL) or serum calcium value is lower than 2.12mmol/L(8 mg/dL) or hypercalciuria (> 0.4 mg/dL GF), or chronic kidney disease (eGFR < 30 mL/min/1.73 m2).
• 5.Patients with a history of malignant tumors.
• 6.Patients judged by investigators to be unsuitable as subjects.