Abstract：Under the premise of ensuring network performance, the key of wavelet neural network(WNN) application and promotion is how to get the most simple network structure by determining the optimal hidden layer nodes. Therefore, a Chi-Square discretization algorithm based on the information entropy and heuristic attribute reduction recursive algorithm is proposed, reduction process of the rough set theory is used to optimize wavelet neural network hidden layer nodes without changing network performance, and an aircraft aerodynamic model is built by modifying wavelet neural network. Simulation results show thatWNNoptimized by the proposed improved rough set method the can not only simplify the network structure, but also improve model accuracy and training speed.