The general mathematics model for aerosol mass measurement by using the counting method is analyzed, and the result indicates that the total mass of aerosol can be expressed as linear addition of counting channels. The light scattering counting method for spherical particles mass measurement was studied as an example. Starting with aerosol mass subset Ni, the fractal relation φ=Lβ between scattering luminous flux of counting channels and aerosol’s average volume can be gained according to statistics. Based on this, the general function (φj )≡ρj=ρL-ηφηj of average mass j and characteristic parameter φ of counting channels can be established, where η is the equivalent section fractal dimension with the range from 0 to 3. In further, all of these were extended to non-spherical particles mass measurement, and then the full mathematics model for aerosol mass measurement founded on light scattering counting method was established. This model provides a feasible way for the counter to measure aerosol mass concentration in real time.