Abstract: The content of ellagitannin, total phenol, and volatile components of Quercus mongolica were determined during the natural seasoning in the opening air. Results showed that the content of total phenolic and some volatile compounds reached stability after seasoned for two years, but the changes of ellagitannin and some undesirable odor compounds such as 2-nonenal, phenol were slowly, and it took three years to reach the level of stability. When the seasoning time got up to four years, the content of phenolic aldehyde and furfural compounds decreased due to the oxidation and volatilization. Therefore, the suitable seasoning time for Mongolia oak was determined as 3 years.