By measuring the precession of the spiral micrometer head，combined with the charaon the experimental principle of Michelson interferometer，a special rotating device is added to the measurement optical path，which converts the tiny rotation of the cuvette containing the transparent liquid into the precession of the spiral micrometer，and accurately controls and records the start and end positions of cteristic change of the hyperbolic diffraction pattern formed，the refractive index of the solution to be measured is calculated，and then the linear relationship curve between the refractive index and the solution concentration is established， which realizes the accurate measurement of the liquid concentration，which not only expands the application scope of the Michelson interferometer，but also innovates the experimental teaching content of the Michelson interferometer．