The change in excitability induced by low-power laser was investigated for freshly dissociated rat hippocampal CA3 pyramidal neuron using the whole-cell patch clamp technique. The experimental results indicate that the activation potential of Na+ channel shifted towards a more negative potential, the peak amplitude of INa increased in a voltage-dependent and reversible manner, the steady-state activation curve and inactivation curve of INa were significantly shifted, the half-activation voltage and the half-inactivation voltage respectively changed from (-4414±528)mV to (-5655±614)mV(n=8,Pn=8, P+ channel, further affect the depolarizing and firing of action potential, and finally be involved in adjusting the excitability of neurons.