Abstract: To explain the peculiar atomization phenomenon that the proportion of different components in the aerosol of e-cigarettes is basically the same as those in the e-liquid, although the boiling points of the main carrier components are quite different, a"non-selective" evaporation mechanism by the binary aerosol forming agents was studied based on their binary phase diagram and capillary evaporation theory. The formation conditions and the process of"non-selective evaporation" were verified by measuring their evaporation temperatures, airflow during heating, using a bespoke capillary experimental platform. The results showed that: 1) Because the surface heating in the porous media, the mass transfer inside the porous capillary were severely hindered, an evaporation layer was formed during the process of capillary evaporation, which was inconsistent with the proportion of the main components in the e-liquid phase. The proportion of the gas-phase components evaporated from the evaporating layer matched the proportion of the liquid-phase components transferred into the evaporating layer to achieve the evaporation-transfer equilibrium. This created a continuous and stable "non-selective evaporation". 2) The difference between the evaporation temperature(T)of glycerol and propylene glycol, and the bubble point temperature(T_b)of the liquid phase of the binary system was 30-49 K. T was very close to the dew point temperature(T_c)of the gas phase with the same component proportion, and the difference was only 4-10 K, indicating that the proportion of the liquid phase components of the surface evaporation layer was significantly different from the proportion of the main components in the liquid phase. 3) Under the surface heating conditions, the evaporation of water-methanol, water-propylene glycol, and propylene glycol-glycerol binary systems deviated significantly from the thermodynamically predicted selective evaporation, thus termed as the"non-selective evaporation". When the porous material was covered with the liquid surface, the evaporation of binary systems further deviated from the selective evaporation. This phenomenon showed that surface heating and mass transfer resistance were the key conditions for the formation of this"non-selective evaporation". 4)The experimental results of the two-stage single capillary evaporation platform showed that the evaporation rate of the water-methanol binary system had an obvious inflection point from fast to slow, indicating that the proportion of components in the evaporation layer changed from being consistent with the e-liquid at the initial stage to being different in the stable"non-selective evaporation"stage. 5)The overall unidirectional liquid flow in the capillary tube was observed by the particle tracing experiment, and no large-scale convective mass transfer and microregional convection existed near the capillary meniscus, which further verified the existence of the"evaporation layer". The experimentally results supported the proposed mechanism of"non-selective evaporation"in its main thermophysical characteristics.