The invention discloses a tobacco insect killing, mold prevention, mellowing and quality guaranteeing comprehensive technology method. The tobacco insect killing, mold prevention, mellowing and quality guaranteeing comprehensive technology method includes the steps of preparing a comprehensive oxygen dropping agent, setting feeding and ventilating channels, setting gas detection systems, and setting a comprehensive technology process including low oxygen insect killing, middle oxygen safe storage mellowing and low oxygen quality guaranteeing storage. The implementation method of the tobacco insect killing, mold prevention, mellowing and quality guaranteeing comprehensive technology method includes the steps of enabling the oxygen concentration inside a tobacco warehouse, namely a tobacco stack, to be dropped to 2% to 3% through oxygen dropping, keeping for 7 days to 15 days to complete the insect killing task, adjusting the oxygen concentration back to 5% to 8% by leading in air to implement the safe storage mellowing, keeping the oxygen concentration of 5% to 8% inside the tobacco warehouse, namely the tobacco stack, in the south for 12 months to 24 months, keeping the oxygen concentration of 5% to 8% inside the tobacco warehouse, namely the tobacco stack, in the central China for 16 months to 24 months, keeping the oxygen concentration of 5% to 8% inside the tobacco warehouse, namely the tobacco stack, in the north for 18 months to 28 months, finishing the tobacco mellowing task, after the tobacco mellowing task is finished, dropping the oxygen concentration to 2% to stop the tobacco mellowing inside the tobacco warehouse, namely the tobacco stack, until tobaccos are put into industrial use, and finishing the quality guaranteeing storage task.