Due to the instability of motor speeds, asynchrony in trigger systems, and mechanical factors, the use of continuous dual-rotating compensator (DRC)-Mueller matrix ellipsometer (MME) is limited. And the stepping one is more often used on an extremely wide spectrum measuring range. However, its long measuring time limits its use. To solve this problem, we propose a weighed factor to judge the stability and robustness of this ellipsometer. This factor describes the performance of ellipsometers better than the condition number. We use this factor as the merit function to optimize the configuration of a 16-point measurement system with an improved genetic algorithm (IGA). Repeated measurement experiments on SiO₂ films revealed that the optimal configuration considerably increased the measurement speed, without a notable decrease in measurement precision. The findings are not only aimed at the optimization of stepping DRC-MMEs; the IGA can also be used for other multiparameter optimization issues, and the weighed factor can be applied for the parameter optimization of other MMEs.