Abstract: Observed the effect of 5% CO₂ inhalation on the threshold recover in guinea pigs after explosi on by the methods of auditory physiology and histochemistry.The results suggested:No effects of 5% CO₂ inhalation on the threshold recover in guinea pigs can be seen in this experiment.If so,the 5% CO₂ inhalation for cure the explosive deafness is not a ideal therapy.