Absorption spectra of 11 illicit drugs were measured by using the terahertz time-domain spectroscopy technique (THz-TDS) in the range 0.2～2.6 THz, and then the absorption spectra of the 11 different illicit drugs were identified successfully by well trained radial basis function (RBF) neural networks. The spectra used for training and identification were normalized before input to the network and the positive identification rate is 96%. The model of RBF neural network was processed in Matlab. The results indicate that it is feasible to apply RBF neural network to the identification of illicit drugs, and the speed of training and identification is fast. The character makes RBF network superior to back propagation neural network (BP) and self-organizing feature map (SOM). Therefore, RBF neural network provides a fast and effective method in the secure inspection and identification for illicit drugs using THz-TDS technique.