Abstract: Applying the weak scattering and thin-screen approximation model,we have evaluated the observation data on the interplanetary scintillation(IPS)of a flareshock on June 15, 1972 by the use of the FFTand Abel transfer approaches.The electron density power spectra of solar wind before and after the shock are computed,respectively. The results suggest that the spectra are in the form of a power law function at small wave numbers (0.001 to 0.009km).The power law index after the shock are greater than those before the shock,implying that the power spectra at the small wave number range become slightly steeper after passing through the shock.