Abstract: In order to investigate the effects of conditioning humidity on the release of aerosols from heated tobacco products (HTPs), the puff-by-puff releases of main aerosol components from two representative commercial HTPs (HTP-1, equipped with central heating device; HTP-2, equipped with peripheral two-section heating device) were determined at different conditioning humidity ranges. Moreover, the influences of conditioning humidity on the puff-by-puff release behaviors of aerosols from those two HTPs were discussed. The results showed that: 1) Both of the two HTPs had their own special puff-by-puff release behaviors and the influences of the conditioning humidity on the puff-by-puff release behaviors of different aerosol components from the two HTPs had regularity as well as particularity. 2) With the increase of the conditioning humidity, the releases of nicotine and glycerin decreased and moisture release increased at the same puff for the first few puffs. 3) Conditioning humidity parameters had obvious influence on the puff-by-puff release trends of nicotine and glycerin in the aerosols from HTP-1, as well as on the variations of nicotine/ACM (the ratio of nicotine to aerosols collected matter) with the proceeding puffs for HTP-1, while it had less influence on those of HTP-2.