To investigate the influence of smoke concentration on the transmission characteristics of polarized light in the smoke environment, carbonaceous particles are used as the research object to study the variation in the degree of polarization (DOP) of linear polarized light in the horizontal, vertical, +45° directions, and right- and left-hand circular polarized light after transmission in different medium concentrations. The Monte Carlo method is used to build a simulation model and analyze the polarization transmission theory. According to the uncontrollable factors for the concentration in actual measurement, the optical depth is applied as the description of the concentration, and the influence of concentration on the transmission characteristics of polarized light is verified by the simulation and the experiment. The results show that DOP of the incident polarized light decreases gradually with the increasing medium concentration. When the linear polarized light in horizontal, vertical and +45° directions is incident, the DOP variation tendency with the concentration is nearly the same as each other. DOP variation trend for the right- and left-hand circular polarized light basically coincides. DOP of the circular polarized light is close to that of the linear polarized light at low medium concentration, and is always higher than the latter at high medium concentration, which demonstrates better polarization-maintaining ability of circular polarized light under low visibility and high medium concentration.