Stray light analysis has great benefits in designing Raman spectrometry system, which is the sensitive detection system of weak optical signal. In this paper, optical design software and Solidworks are utilized to optimize the optical and mechanical structure. The system resolution is 0.7 nm, and the volume is 110 mm×95 mm, which belongs to portable and miniature Raman spectrometer. Based on the stray light simulation model, we made an analysis of ray tracing simulation for this system. First, the stray light come with the incident ray were suppressed by the aperture stop. Then the receiver of stray light was introduced and improved in the design progress to suppress internal stray light, especially for zero-order diffraction light of plane grating. The improved receiver of stray light is more effectively using the internal space of the spectrometer and analysis results show that a 50% reduction in the number of stray light and stray light normalized irradiance intensity from 10-5 down to 10-7. The analysis shows that the improved receiver of stray light can effectively suppress stray light, which is beneficial to weak signal detection, and provide reference for design and adjustment of the miniature Raman spectrometer.