Based on the engineering fact of Diaozhongba slope, an optimization method of BP wavelet neural-network was used to predict displacement of slope. The method used conjugate gradient back propagation algorithm optimizing BP-WNN parameters, reduced large amount of network calculation volume, avoided the drawbacks of local optimum result and improved the quality of the network. Compared with non-optimized BP wavelet neural-network, the predicted values measured by the optimized BP wavelet neural-network were more close to those measured by GPS.