Abstract: In order to evaluate the vapor mass concentration of e-cigarette aerosol and to investigate its influencing factors, a method for quantitatively characterizing the mass concentration of e-cigarette aerosol via optical transmittance was established. The effects of machine puffing parameters, solvent types and concentrations in e-liquid, coil working voltage and coil resistance of e-cigarette on the vapor mass concentration were investigated by adopting the developed test system. The results showed that:1) Under constant puffing volume, the vapor mass concentration was larger at a shorter puffing interval. 2) When the mixture of glycerol and 1, 2-propylene glycol was used as the solvent of e-liquid, the mass concentration of e-cigarette aerosol was higher than that of a single solvent. 3) Under the same puffing condition, the output power of e-cigarette coil positively correlated to the mass concentration of the aerosol produced. This characterization method and the developed test system are reasonable, effective, and suitable for real-time quantitative analysis of the mass concentration of e-cigarette aerosol.