Abstract: Since Xu and White established the effective medium model about sand-clay rock (Xu-White model) in 1995, many geophysicists have predicted shear velocity by this model and its improved model. But few of them have made detailed review of the uncertain factors in the process, this paper firstly introduced the Xu-White model and its prediction flowchart, and then made a detailed analysis on the uncertain factors in the process of prediction, which can make researchers choose more reasonable parameters to predict more effectively shear velocity according to the actual geological conditions.