In the randomized, active-controlled, double-blinded, multicenter study, the efficacy and safety of monthly oral minodronate were examined and compared to that of weekly oral alendronate.

Inclusion Criteria:

1. Women aged 46-80 years, menopause for more than 1 year, free to move，Estradiol ≤20pg/mL and follicle stimulating hormone ≥40IU/L in patients with simple hysterectomy;
2. Body mass index (BMI) is 18.5-30.0kg/m2, including critical value, BMI= weight (kg)/height 2 (m2);
3. Based on dual energy X-ray absorption (DXA)Determination, bone density (BMD) determination of lumbar vertebrae L1-L4 (At least 2 consecutive lumbar vertebrae for accurate measurement of BMD ) mean T ≤ -2.5SD, or T≤ -2.5SD on either side of the double hip femoral neck;
4. Understand the procedures and methods of this clinical study, voluntarily participate in and sign the informed consent form.

Exclusion Criteria:

1. Patients with conditions that affect BMD measurement, such as severe scoliosis or any lumbar L1-L4 fracture or hip fracture;
2. Patients with secondary osteoporosis;
3. Endocrine diseases or other diseases affecting bone metabolism that the investigator considers inappropriate, such as gonads, adrenal glands, primary parathyroid dysfunction, or malformed osteitis (Paget's bone disease), nephrotic rickets, osteomalacia, rheumatoid arthritis, osteogenesis imperfecta , poorly controlled hyperthyroidism or hypothyroidism;
4. Patients with serious primary diseases such as cardiovascular, cerebrovascular and hematopoietic system, and mental or nervous system diseases;
5. Patients with abnormal blood calcium: serum calcium or serum calcium corrected by albumin ≤2.0mmol/L or ≥2.9mmol/L;
6. Parathyroid hormone > 1.5 times the upper limit of normal;
7. Patients with severe gastrointestinal absorption dysfunction such as dysphagia, esophagitis, enteritis or peptic ulcer，crohn's disease and chronic pancreatitis;
8. Patients with delayed obstruction of the esophagus, such as narrow or loose esophagus;
9. patients has previous or co-existing malignancies (except skin basal cell carcinoma and carcinoma in situ of the cervix, which have been cured for more than 3 years);
10. The patient who are deformed, disabled, unable to work or in a critical condition; which difficult to evaluate the effectiveness and safety of drugs accurately ;
11. Patients with type 1 diabetes or type 2 diabetes with poor glycemic control and severe acute and chronic complications;
12. Patients had received any other investigational drug/device treatment within 3 months prior to enrollment;
13. Patients with renal insufficiency or severe renal impairment(Ccr<35mL/min);
14. Patients with abnormal liver function (ALT or AST≥2.0 times the upper limit of normal);
15. Allergic constitution or allergic to study related drugs (calcium, vitamin D, minodronic acid or similar drugs);
16. Hepatitis B surface antigen (HBsAg) positive or hepatitis B core antibody (HBcAb) positive with HBV-DNA positive, hepatitis C virus (HCV) antibody positive with HCV-RNA positive, human immunodeficiency virus (HIV) positive, syphilis antibody positive;
17. The patients has previous or co-existing osteomyelitis or osteonecrosis of the mandible, the patients have dental surgery such as tooth extraction during the first 2 months of enrollment or during the trial;
18. The patients with a history of drug abuse or alcohol abuse within 6 months prior to enrollment;
19. The patients used the following drugs before enrollment: used oral bisphosphonate more than 3 months within 1 year or the cumulative use of oral bisphosphonate more than 1 year; used desomumab within 1 year;used intravenous bisphosphonate within the past 5 years;patients daily used systemic corticosteroid equivalent to prednisone > 5mg more than 14 days within 2 months (local external use is excluded) ;used calcitonin or active vitamin D complex within 6 weeks; used selective estrogen receptor modulators or estrogen replacement therapy for more than 1 month within 6 months;Qianggu capsule, total flavone of Epimedium, Jintiange capsule, Xianling Gubao capsule, Qigu capsule, Gushukang capsule and Zuogui pill were used for more than 3 months in 6 months;
20. Other patients that the investigator believes are not suitable for enrollment.