The computation of the Moore-Penrose inverse is widely encountered in science and engineering. Due to the parallel-processing nature and strong-learning ability, the neural network has become a promising approach to solving the Moore-Penrose inverse recently. However, almost all the existing neural networks for matrix inversion are based on the gradient-descent (GD) method, whose main drawbacks are slow convergence and sensitivity to learning parameters. Moreover, there is no unified neural network to compute the Moore-Penrose inverse for both the full-rank matrix and rank-deficient matrix. In this paper, an efficient second-order neural network model with the improved Newton's method is proposed to obtain the accurate Moore-Penrose inverse of an arbitrary matrix by one epoch without any learning parameter. Compared with the GD-based neural networks for Moore-Penrose inverse computation, the proposed model converges faster and has lower complexity. Furthermore, through in-depth derivation, the neural network for computing the Moore-Penrose inverse is well interpretable. Numerical studies and application to the random matrix inversion in multiple-input multiple-output detection are provided to validate the efficiency of the proposed model for solving the Moore-Penrose inverse.