In this paper, a new one-way Hash function is proposed based on chaotic neural network. With the neural network with piecewise linear chaotic map as the output function, the key generation function based on spatiotemporal chaotic system are used to realized the data confusion and diffusion. By the cipher block chaining mode, the proposed method can produce 128-bit Hash value for plaintext with arbitrary length. Theoretical analysis and experimental results indicate that the proposed Hash function satisfies the demands in performance, such as being one-way, having initial value and key sensitivity, collision resistance and real-time applicability.