OBJECTIVE： To evaluate the economics of alendronate sodium preventing osteoporotic fractures in postmenopausal women， and to provide reference for osteoporotic and osteopenia patients to select economical and effective therapy plan. METHODS： Using Markov economic model， TreeAge Pro 2011 software was used for cost-utility analysis using RCTs literature data of basic medication （calcium and vitamin D3） and basic medication combined with alendronate sodium as baseline data. Using quality adjusted life years （QALYs） and incremental cost utility ratio （ICUR） as economics evaluation indexes， the stability of established model was investigate by single factor sensitivity analysis. RESULTS： QALYs of the basic treatment group was 0.704 years， and QALYs of drug combination group was only 0.708 years. However， ICUR of two groups reached 714 252.44.  For the late period of hip fracture and other fractures， drug combination group was in high cost and low benefit， obviously had no economic advantage. For vertebral fractures， the cumulative probability of fracture in drug combination group was significantly lower than basic treatment group， and ICUR of the two groups was only 13 902.17， with economic advantage. For hip fracture， the cumulative probability of fracture in basic treatment group was the same as drug combination group， and ICUR was 19 109.00， with economic advantage. For wrist fractures， curative effect and economy needed further study. CONCLUSIONS： For the low-risk population with osteoporotic fractures， calcium and vitamin D3 are more economical in preventing osteoporosis fractures. For the high-risk population with vertebral and hip fractures， alendronate sodium combined with basic treatment is effective and economical.