With alcohol solution，NaCl solution and sucrose solution as research objects and Michelson interferometer as carrier，the relationship between refractive index and concentration of these solutions at 20 ℃ was studied by titration．By fitting the variable relationship between the concentration and the refractive index， the functional relationship n(c)of the refractive index n with the concentration c is obtained by integral operation，and then the refractive index of the solution at any concentration is given．This experiment can not only be used as a design experiment or an extension experiment of college physics to cultivate students’ practical ability and innovative ability，but also can be used to measure the refractive index of solutions at different concentrations．It would have a good prospect in application．