Concentration is one of the important parameters of the solution．An on-line measurement system of the solution concentration/refractive index was designed based on the rotating cuvette and Michelson interferometer．Adding the resolution in the cuvette and rotating the cuvette 5°，the number of moving fringes was measured by the intensity curve imaged by CCD and the counting program，and the refractive index and concentration of the solution could be measured，respectively．Taking the NaCl solution with concentration of 0，10% and 20% into consideration，the relative error as compared with the theoretical value is only 0．61%，0．63% and 2．2%，respectively． Meanwhile，the glucose solution curve between the refractive index and concentration presents good linearity and high reliability． The online system measurement of solution concentration/refractive index based on Michelson interferometer has the characteristics of simple design，reliable results，high efficiency and practicality．