Objective: To investigate the characteristic of Extended High Frequecy DPOAE for the Idiopathic Tinnitus patient with normal hearing threshold,and investigate the clinical values for finding the earlier hidden hearing loss with Extended High Frequency DPOAE. Method: The experimental group was including 68 tinnitus subjects with normal PTA (104 ears) , and control group was including 40 normal PTA subjects without tinnitus (40 ears) , both of two groups subjects were measured the routine DPOAE( frequencies ranged from 1-6kHz) and Extended 8-12kHz DPOAE by using Neuro-Audio Otoacoustic Emission Analyzer. Result: The detectable rate of routine DPOAE measurement for control group was 97.225%, and Extended High Frequency DPOAE 88.7%; the routine DPOAE for experimental group 72.2%, Extended High Frequency DPOAE 51.23%. the averaged DP level of control group for frequencies 8 kHz、10 kHz、12 kHz were 3.00、1.75 and-2.90dB, the experimental group were -8.39、-11.55 and -17.93dB. the averaged SNR of control group for frequencies 8 kHz、10 kHz、12 kHz were 11.4119、10.6407 and 5.4898dB, the averaged SNR of experimental group for frequencies 8 kHz、10 kHz、12 kHz were 4.4795、2.4419 and -3.8128dB.The detectable rate of Extended High Frequency DPOAE for experimental group was significantly lower than the control group（P<0.001）,and also was significantly lower than the routine DPOAE measurement（P<0.05）, the DP level of Extended High Frequency DPOAE for experimental group was also significantly lower than the control group（P<0.001, and the averaged SNR of experimental group was significantly lower than the control group（P<0.001）. Conclusion: The detectable rate of Extended High Frequency DPOAE was significantly lower than the routine DPOAE measurement for normal PTA subjects with tinnitus ,the DP level of Extended High Frequency DPOAE was decreased significantly, indicated that the Extended High Frequency DPOAE has higher sensitivity in diagnosis the hidden hearing loss for the Idiopathic Tinnitus Patient with "Normal Hearing" than the routine DPOAE measurement, and can reflect the earlier functional status of cochlear outer hair cell.