Abstract: The quantitative analysis method of slag content in aluminum alloy melt was introduced. Taking the off-line slag test sample of 7055 aluminum alloy melt as an example, the test results of the two methods were analyzed. The results show that the precision of the test results of the metallographic software analysis method was higher, the data dispersion was small, and the specific operation steps of the metallographic software analysis method were provided. According to the proportion of the picture and the area corresponding to each pixel under the magnification, the area of the metallographic examination photo could be calculated more accurately.