The aim of this in vitro study is to explore the correlations between quantitative ultrasound (QUS) parameters and micro-structure parameters of cancellous bone. Cube of swine cancellous bone were resort to progressively decalcification and subjected to QUS and micro computed tomography. Ethylene Diamine Tetraacetic Acid (EDTA) decalcification was used to remove calcium. SOS, an important QUS parameter, has a downtrend as calcium run off. At the same time, both BV/TV and Tb.Th have a downtrend; meanwhile, BS/BV and Tb.Pf have an uptrend during the process of decalcification. SOS shows a great correlation with Micro-Structure parameters which indicate that quantitative ultrasound has the potential to reflect bone microstructure.