Abstract: There are potential of polarization signal enhancement in smog environments at shortwave infrared wavelengths. The polarization characters for forward propagation at 532 nm and 1550 nm wavelengths were investigated by experiments. The smoke environment was made by burning smoke cake. It mainly composes of NH₄Cl particles and water vapor. NH₄Cl particles deposited stably when smoke cake burned in 7-16 min. The laser test platforms at 532 nm and 1550 nm wavelengths were developed to measure forward propagation character of horizontally linearly polarized light. Measurement errors of 532 nm and 1550 nm laser test platforms were nearly 1.03% and 0.89%, respectively. It mainly included fluctuation error of laser, time variation error, installation error and rotation error. The polarization state retention rate RoPS was tested when smoke cake burned in 7-16 min. The experimental results show that horizontally linearly polarized light has superior forward propagation performance at 1550 nm wavelength. And as the smoke concentration decreases, the difference of RoPS values gradually reduce. The work verifies the persistence of horizontally linearly polarized light at 1550 nm wavelength. It can provide experimental support for application of infrared polarization technology.