To study the basic properties of DPOAE including the Spectral History of DPOAE in subjects with normal hearing, Thresholds of octave pure tone from 0.125 to 8 kHz and Tympanometry in 226 Hz were measured to exclude the abnormal function of middle ear in 38 ears of 19 young subjects, then the spectrum of DPOAE、DP - Gram、I/O function curve、Latency and Spectral History of DPOAE were recorded. DPOAE can be detected in all subjects, the amplitude of DPOAE has great intersubjectal variety, the largest two values are 9.11 dB SPL at 1. 5 kHz and 7.72 dB SPL at 6 kHz, DP - Gram has two peaks. The amplitude increased with the increasement of primary tone level, The latency shortened with the increasement of primary frequency. The Spectral History in most of them is flat, the coefficiency of variance is 2. 53?1. 89% , the abnormal rate is 18.5% implying the Spectral History maybe have role in predicating subclinic cochlear lesion.