Abstract: The response of ionospheric scintillation to 3 geomagnetic storms in year 2004 are analyzed by using plasma density in-situ observations onboard CHAMP satellite and GPS ionospheric scintillation monitor (ISM) at Haikou. It is found that the characteristics of the ionosphere are quite different. In terms of B_z component and Dst observation, the strength of geomagnetic storm in November is the strongest, followed by it in January, and the geomagnetic storm in February is the weakest. However, the observations from the ISM show that, the L-band ionosphere scintillation is strongest during the January geomagnetic storm, the peak S₄ value and peak scintillation occurrence is close to 1.0 and 80%, respectively. The duration of ionospheric scintillation is the longest during the February geomagnetic storm, with the peak S₄ value and scintillation occurrence close to 1.0 and 63%, respectively. During the main phase and recovery phase of the November magnetic storm, there is no ionospheric scintillation. The observation derived from CHAMP satellite is in consistent with that from ISM. The results show that the large scale ionospheric irregularities tend to appear when the small scale irregularities are present, but the small scale ionospheric irregularities usually disappear first. We conclude that the differences in the response of ionospheric are mainly related to the effect of ring current, which could be well explained by Aarons' criterion. The neutral wind may also have contributions to these differences.