To improve the performance of the clutter suppression and small target detection, a detection algorithm for a small target in sea clutter was proposed, based on the spatio-temporal chaos analysis. First, the sea clutter phase space was reconstructed as a chaotic dynamical system, and the chaotic parameters of the sea clutter sequence image were extracted to verify that the sea clutter owns chaotic properties in the spatial and temporal domains. Furthermore, the spatial chaotic reconstruction function, the temporal chaotic reconstruction function, and the space-time coupling coefficient were estimated by the radial basis function neural network. Finally, the spatial and temporal chaotic functions were integrated jointly to reconstruct the spreading regularity of the moving sea clutter. Some experiments were induced on the small target in various fluctuating sea clutter, and the experimental results show that the proposed algorithm, can improve the performance of the sea clutter suppression and enhance the small target detection ability, with the prediction error reduced by 10% and the detection probability increased by 20%.