In order to probe the influence of the different concentration of tea solution on the electrophysiological character of toad’s sciatic nerves, the toad’s sciatic nerves were immersed in different groups of solution respectively: normal Ringer’s solution and different concentration of tea solution. After the different intervals of immersion time, the width, the amplitude, threshold intensity, refractory period, conduction velocity of the action potentials of the sciatic nerves from each group were measured respectively. The results showed that the lower concentrations of tea solution increased the amplitude and the conduction velocity of the action potential; but the width, threshold intensity and the refractory period of the action potential of the sciatic nerves were decreased. The case was reversed when the solution concentration was raised and the interval was prolonged. This can be concluded that the excitability of nerves could be increased by the lower concentration of tea solution, but it could be decreased as the solution concentration was raised and the interval was prolonged.