Abstract: The foundation deformation of nuclear power plant nuclear island is observed during the whole construction process. Different sites are with different values of foundation deformation that are with different effects on the items crossing buildings at the completion of the raft foundation of the nuclear island. In this paper, the data from 15 times of observation of the foundation settlement in a nuclear power plant are analyzed. Firstly, the observation data is disposed by the wavelet denoising technology. The pretreatment result shows that the foundation settlement is highly time dependent and tends to steady according to the foundation settlement velocity. . Based on the above, a 3 times short-term prospect and a 30 years long-term prospect are predicted with hyperbolic method and gray theory method. In short-term prospect aspect, two methods, especially the gray theory method, are both conservative comparing with the actual observation result. As for the long-term prospect, the gray theory method is inapplicability for its result diverges. While the prospect with hyperbolic method is effective comparing with the foundation settlement data of two typical nuclear power plants which have operated for 30 years.