Abstract: In order to study the chemical composition of aerosols from heated tobacco products(HTPs)and to investigate the puff-by-puff release characteristics of aerosols from HTP samples, an online sampling device for HTP aerosols was developed by adopting a valve injection technique. Using this technique, HTP aerosols were directly introduced into gas chromatography-mass spectrometry(GC-MS)by carrier gas(helium)through an inline heating transmission line without sample loss. The results showed that: 1)The online HTP aerosol analysis system had a stable performance and good reproducibility. 2)The contents of acetone and 2-butanone determined in the aerosols of sample A by this method was in good accordance with the results reported by literature. 3)With the proceeding of puffing, the releases of acetone and 2-butanone from the aerosols of sample B increased first and then decreased. This method is simple, efficient and suitable for the online analysis of the whole aerosols of HTPs and the puff-by-puff release characteristics of HTP aerosols.