Performance of non-line-of-sight (NLOS) ultraviolet (UV) communication is closely related with the communication range, system geometry and the atmosphere aerosol properties. In this paper, we investigate the path loss of the NLOS UV communication systems in both monodisperse and polydisperse aerosol systems based on the Monte-Carlo method. The mixed aerosols composed of black carbon and sulfate are considered as the transmission media. The core-shell, homogeneous, and external mixing model are assumed. Simulation results show that the performance of the NLOS UV communication in the monodisperse aerosol is similar to that in polydisperse aerosol. The mixed state of the aerosols has significant influence on the performance of the communication system. The path loss of the communication system in externally mixed aerosol is smaller than that in internally mixed aerosol. Our simulation results are useful for the design of the NLOS UV communication systems.