Abstract: The QTM experimental equipment developed by the authors was used to conduct controlled atmospheric drying experiment on vegetables. Under different temperatures, the effects of gas composition on the dehydration of balsam pear pieces, turnip slice and sweet onion were analyzed. The results showed that under various temperatures and decreasing O₂ content in the drying media, in which N₂ and CO₂ were used as drying media to replace partial air, the chlorophyll content and mass fraction of vitamin C of the vegetables were improved. When the exponent function was used to fit the relationship between the O₂ content and the effect of the chlorophyll content of vegetable and the power function was used to fit the relationship between the O₂ content and the mass fraction of vitamin C of the vegetables. The confidence levels of regression equation of factor indices are greater than 95%.