为定量研究激光冲击镁合金晶粒的细化率，以镁合金激光冲击区表层的金相图像为研究对象，设计出了针对性的分析方法。对激光冲击区和未冲击区的镁合金的金相图像进行了灰度增强处理、中值滤波处理、二值化处理、数学形态处理等，并利用截距法计算出冲击前后晶粒的平均直径和激光冲击后晶粒的细化率。研究结果表明，该研究方法可以方便快捷地处理镁合金的金相图样，并可以准确地定量计算出激光冲击强化镁合金前后的晶粒平均直径、平均直径细化率，通过定量分析，得知直径细化率为70.43％。

In order to study the refinement ratio of magnesium alloy grains, metallography of shocked area by laser of magnesium alloy was observed, and pertinent analysis methods were worked out. Deal with the metallography of the specimens on the shocked and non-shocked area by grey enhancement processing, median filtering processing, binarization processing, mathematical morphological processing and etc, and the average diameter of the grains before and after the laser shock peening (LSP) and the refinement ratio after the LSP were worked out. It showed that the research methods could process the metallography of magnesium alloy conveniently and quickly, the grain size before and after the LSP and the refinement ratio after the LSP were worked out, and the refinement ratio was 70.43％by quantitative analysis.