To solve the problem of discrepancies between calculation results and test results of the polarization meridian Monte Carlo method, an improved algorithm which can limit receiving range was proposed. All forward scattered light was received generally in real receiving devices in the process of calculation, but part of forward scattered light was collected. This is one of the important factors causing discrepancies and mismatch between calculation results and test results of the polarization meridian Monte Carlo method. For this reason, an improved algorithm was proposed to limit receiving range of forward scattered light. Receiving range of the improved algorithm was consistent with real receiving range. Original algorithm and improved algorithm were used to simulate the propagation of 45°- and horizontally- linearly polarized light in polystyrene suspension, respectively. Then, the polystyrene suspension with particle size of 1 μm were selected to carry out verification experiments. Compared with the original algorithm, simulation results of the improved algorithm were closer to measured values. Finally, the polarization state distribution of a single particle was calculated to clarify mechanism of improved accuracy. Retention of polarization state(RoPS) changes drastically as forward scattered angle extends. Improved algorithm avoids most of forward scattered light with larger forward scattered angles.