The particle size and distribution characteristics of exhaled aerosol particle fields are related to the health status. This study proposes a diagnostic method for exhaled aerosol particle fields using coaxial digital holography. A connected domain method was employed to extract particle sizes from the reconstructed images of exhaled aerosol particle field holograms, determine particle size distributions, and calculate statistical parameters (D₁₀, D₃₂, D₄₃, and D_N50). The method was tested on 14 healthy volunteers and 10 infected patients to obtain the distribution and average values of two sets of particle size statistical parameters. The detection accuracy within the distribution range of particle size statistical parameters was calculated, and benchmark points for each statistical parameter were obtained. Using the four benchmark points and average particle size statistical parameters as indicators, six test volunteers were tested. By minimizing the accuracy and coefficient of variation, the Sauter mean diameter is identified as the optimal criterion for assessing the health status, achieving a detection accuracy rate of over 80%. This study introduces an optical method for the preliminary diagnosis of influenza through the analysis of exhaled aerosol particle fields.