Abstract: The effects of temperature,flow rate of N2,concentration of O₂ on the formation of 8 volatile carbonyl compounds from pyrolysis of glycerol and 1,2-propylene glycol were studied with orthogonal experiments to investigate the influence of the humectants on sensory quality and toxicity of cigarette smoke.The results showed that:1)The flow rate of N2 was a main factor affecting the formation of formaldehyde,and the temperature was a primary factor affecting that of the other carbonyl compounds except for acrolein and crotonaldehyde from pyrolysis of 1,2-propylene glycol;2)The yields of formaldehyde,acrolein,and crotonaldehyde from glycerol were higher than those from 1,2-propylene glycol significantly;while at 800℃,the yields of acetone,propionaldehyde and methyl ethyl ketone from 1,2-propylene glycol were much higher;3)The difference of yields of formaldehyde,acetic aldehyde,acrolein,propionaldehyde and acetone from glycerol and 1,2-propylene glycol might be caused by the difference of energy of C-O and C-C bonds in the two humectant molecules;4)The propylene glycol as a humectant for cigarette was preferable to glycerin in terms of sensory quality and toxicity of cigarette smoke.