Abstract: Considering some defects of BP Neural Network, the idea that the power size and the threshold value of the network structure is optimized by combining genetic algorithm with neural network is presented. Based on genetic algorithm, the prediction model of loosen zone around roadway is built. Finally, the prediction on the thickness of the loosen zone around roadway is made with this GA- BP model, and the results are compared with the BP predicting results. The result shows that the GA- BP model is reliable and precise, and it is effective and feasible to predict the thickness of the loosen zone around roadway.