The present invention relates to a rapid quantitative analysis method that utilizes infrared spectrum to analyze the composition of a mixed solution, characterized in the analysis method for establishing a FT infrared spectrum liquid pool to measure the composition of methylbenzene/alcohol cleaning solution quantitatively. The method comprises the following steps: taking the characteristic absorption band of methylbenzene at 1600cm<-1> and the characteristic absorption band of alcohol at 880cm<-1> as the reference for quantitative analysis, and utilizing a theory based on Lambert-Beer Law to fit a working curve of mapping relation between the absorbance ratio of characteristic absorption band and the concentration ratio of components. The working curve has good linearity and a correlation coefficient R<2>=0.998. The result of analysis of the samples with the method indicates the relative error of the method is 6.6 percent and the method is highly feasible and reliable to use in industrial production. The present invention is characterized in simple process, easy operation, quick comparative analysis, and low cost, and can be widely used in industrial production.