We establish a preliminary model of neural signal generation and transmission based on our previous research, and use this model to study signal transmission on unmyelinated nerves. In our model, the characteristics of neural signals are studied both on a long-time and a short time scale. On the long-time scale, the model is consistent with the circuit model. On the short time scale, the neural system exhibits a THz and infrared electromagnetic oscillation but the energy envelope curve of the rapidly oscillating signal varies slowly. In addition, the numerical method is used to solve the equations of neural signal generation and transmission, and the effects of the temperature on signal transmission are studied. It is found that overly high and overly low temperatures are not conducive to the transmission of neural signals.