The extraction of absolute oil from tree moss with supercritical CO₂ fluid was studied systematically. The effects of extraction pressure, temperature, time, CO2 flow rate, and the rate of entrainer on the quality and yield of the absolute oil was investigated. The determined optimum extraction condition was that extraction pressure was from 15 to 18MPa, extraction temperature 40 °C, CO2 flow rate 2 to 3L per hour, entrainer flow rate 20 to 30mL per hour, and extraction time 3 hours. The yield of the absolute oil was 2.03%. The panel results of tested cigarettes flavored with the absolute oil showed that the absolute oil was capable of enhancing tobacco flavor, masking offensive odor, reducing irritation, and obviously improving smoking taste. It was concluded that: 1) the absolute oil could not be efficiently extracted from tree moss with supercritical CO₂ fluid unless entrainer was added to extracting agent; 2) feasible absolute oil for tobacco was extracted only under right extraction condition; and 3) the absolute oil of tree moss was an ideal tobacco flavor.