Objective: It is extensively found that hippocampal function plays an important role in the ethanols effect on spatial learning.But extracellular electrophysiological aspects is mostly used in vitro.So in order to analyze the firing characteristics and differences of neuronal population,the multi-channel local field potential(LFP)and spike potential(spike)on the hippocampus CA1 were recorded during the awake state and the period of acute ethanol administration in vivo.Methods: Ten ICR mice were selected and micro-electrode matrix were implanted in the hippocampus CA1 of the mice,LFPs and spikes were recorded from the waking mice using the Data Acquisition System.Then the mice were intraperitoneal injected with dose of 1.5g/kg ethanol.Thirdly,Multi-channels electric signals were recorded every 20 minutes until four times.We got various parameters by calculating multi-channels electric signals value.Results: We detected that the mice hippocampal CA1 area of average firing frequency in waking status was significant higher than the average firing frequency in acute alcohol administration status(P < 0.05).We also found that ISI and alpha band power spectrum values in waking status was more than that in acute alcohol administration status(P < 0.05),and By contrast,these parameters would gradually recover between 40 to 60 minutes in acute alcohol administration status.It is indicated that acute alcohol administration decrease the hippocampus neuron excitability activities Conclusion The result suggest that a major mechanism of ethanol actions on Hippocampal CA1 area is an ethanol-induced deafferentation at the input stage of the hippocampal function in the form of excitatory neurons inhibition in vivo.