Abstract: Objective Based on GNSS observations from the IGS,this paper reconstructed the 3Dspatial and tem-poral distribution of ionospheric electron density over Europe during three strong magnetic storms in2003-2006,using computerized ionospheric tomographic technology(CIT).The reconstructed imagespresent the 3Dstructure of ionospheric electron density.By analyzing the evolutionary process of ion-ospheric disturbances,the paper shows that ionospheric responses are coincident with the developmentof magnetic storms;and further that such disturbances have a remarkable latitudinal effect.Addition-ally,the altitudes where electron densities are the maximum also changed during the magnetic storms.The research and analyses in this paper illustrate that CIT can reflect the distribution and involvementof electron densities in each longitude,latitude,and altitude lane.CIT is shown to be useful for im-proved analyses of ionospheric disturbances during magnetic storms.