The refractive index changes near the absorption edge in semiparabolic quantum wells are examined as a function of the incident optical intensity, and an analytic formula for the changes in the refractive index is obtained by using the compact-density matrix approach and an iterative method. Numerical results are presented for some typical AlGaAs/GaAs quantum wells. The calculated results show that the incident optical intensity and the semiparabolic confinement frequency have a great influence on the total refractive index changes.