In order to make the spatial amplitude modulation polarization spectrometer have the minimum sensitivity to the system error, we take the condition number of the measurement matrix as the objective function, and use the genetic algorithm to simulate and analyze the optimal combination of the double composite optical wedge crystal axis azimuth and the polarizer azimuth in the modulation module of the instrument, and give the corresponding optimal angle combination. With the measurement accuracy of the degree of polarization as the evaluation function, the simulation experiment is carried out for a variety of different angle combinations within the given device error range. Simulation results show that According to the simulation results, when the measurement matrix condition number of the instrument angle parameter combination is 1.733, there is a 98% chance that the polarization degree measurement accuracy will be better than 0.01, this probability is 23% and 64% higher than the probability for the angle parameter combination with the measurement matrix condition number of 1.966 and 3.257, respectively. This study provides a theoretical basis for the design and selection of the parameters of the spatial amplitude modulation polarization spectrometer components.