Abstract: To investigate the effects of filter base rods of different materials and lengths on the absorbance of heated tobacco product(HTP)aerosol, a commercial HTP was modified as the aerosol source, and 12 base rods consisting of cavity acetate fiber section, PLA section and acetate fiber section with lengths of 5, 10, 15, and 20 mm were separately connected to the aerosol source and prepared as test samples. The absorbance of the aerosol generated was measured by the light transmission method, and the change of the absorbance relative to the aerosol source sample was taken as the absorbance attenuation rate. The influence of different filter base rods on the aerosol absorbance was analyzed. The results showed that: 1)The coefficient of variation of the aerosol source absorbance from the third to the sixth puff was less than 6%, which was relatively stable. 2) The longer the base rod, the higher the attenuation rate; there was some differences in the degree of the base rod lengths on the puff-by-puff attenuation rate. The length of the cavity base rod and the PLA base rod had an exponential relationship with the puff-by-puff attenuation rate, with R² greater than 0.90, except for the first puff. The length of the acetate fiber base rod had a linear relationship with the puff-by-puff attenuation rate, with R² greater than 0.87, except for the second and fifth puffs.