Abstract: To deeply understand the role of diammonium phosphate (DAP)/urea (UR) compound additives in the quality improvement of reconstituted tobacco, the differences of the thermal decomposition process and the formation of carbonyl compounds between DURTS and RTS (the reconstituted tobacco sheet with and without DAP/UR system) were investigated. The results showed that: (1) compared with RTS, the second (142-275℃) and fifth (539-710℃) thermal degradation stages of DURTS gradually disappeared, and the maximal rate of weight loss during the fourth (372-539℃) thermal degradation stage reduced from 8.9 %/min to 6.9 %/min while the peak temperature (T_p4) increased by 11.2℃; (2) the end temperature of the second exothermal stage was increased from 532℃ to 564℃, which suggested that the thermal stability of RTS was enhanced by DAP/UR system; (3) the DAP/UR system inhibited the production of carbonyl compounds during the thermal decomposition process of reconstituted tobacco sheet, the yields of total carbonyl compounds reduced by 21.6%; (4) DURTS was obviously superior to RTS in terms of aroma quality, concentration, irritation, offensive odor and aftertaste, especially in reducing irritation and offensive odor.