This paper gives the relation between the Fourier and Bessel power spectra of ionospheric scintilation and the fluctuations in electron density of irregularities when a thin phase-screen approximation is justifies.And analysed the data obtained by Riometer with narrow lobe-beam antannas.It shows that the Riometer data contain the information of irregularities in the ionosphere,and these data could be used to study the ionospheric scintilation.