The solvent concentration distribution in the curing process of the acetone/polymethyl methacrylate (PMMA) coating solution is measured by the laser confocal Raman spectroscopy method. The Raman spectra of acetone, PMMA, and acetone/PMMA coating solutions with different mass concentrations are respectively measured, and the relationship between the peak intensity ratio and the mass concentration ratio of PMMA to acetone is established with the least squares method. The experimental results show that the linear correlation coefficient of the calibration curve is above 99.9%. The peak intensity ratio of PMMA to acetone can be obtained from the spectra by real-time measurement and subsequently the solvent concentration at this moment is obtained.