Abstract: To study the influence of impurity particles on light propagation in air, a finite element method was used to analyze the distribution of light intensity at the boundary of impurity particles at the presence of multiple impurity particles. The intensity difference data between different particles was acquired. A general solution was provided to solve the problem of complex impurity particles. After theoretical analysis and experimental verification, the results show that, for sphere particles, while there are two impurity particles at the same time, the particles passing through the impurity present a trend from low to high, and the intensity reaches the maximum in the area where the impurity particles are in contact with each other. For cube impurity particles, the intensity distribution exhibits a strong fluctuation property, and the intensity of light is 100 times more than that of sphere impurity particles. The research model has strong portability and can be widely applied to lots of fields. This result is helpful for the subsequent development of light propagation in air.