The firing activity of neuronal membrane potential is the basis of neural coding. However, to date, a complete understanding of the way by which neuronal electrical activity codes neural information has not yet been established. The traditional coding theory holds that the nervous system expresses and transfers information in discrete firing sequences of action potential, mainly studying the firing frequency of action potential and the time pattern of firing activity. Based on this theory, some quantitative calculation methods have been presented for the information carried by the neuronal spike trains, but these methods are still difficult to be applied in the calculation of largescale neural networks. In the present study, the membrane potential of neurons was used as the study object. Analysis was performed regarding how to quantify the information carried by the membrane potential trains, and the calculation results were compared with results calculated by the traditional neuronal spike trains method, and good consistency was obtained. This study provided a new idea and method for the quantitative calculation of neural activity information.