Abstract: Evaluating bone regularly is important to prevent and control the disease of osteoporosis. Impact of osteoporosis on ultrasonic guided waves propagating in human long bones is studied in this paper. Multi-scale wavelet transform is proposed to process the received guided waves, and by analyzing energy changes in detail components of high order wavelet at different propagating distance to assess if osteoporosis happened. The guided waves signals are collected from the tibia of 13 volunteers. Based on the analysis of multi-scale wavelet transform, the main frequency of 7 volunteers changed dramatically with the propagation of ultrasonic guided wave along long bones, which means these 7 volunteers are diagnosed with osteoporosis. Compared with X-ray diagnosis, the accuracy of this method can reach 92.3%. This suggests the multi-scale wavelet transform method is potential in ultrasonic assessment of bone quality.