Abstract: four features of the 2-day oscillations of the equatorial anomaly(Here after abbreviated as TDOEA) are revealed. The superposition of the planetary scale oscillations of the equatorial anomaly with different periods are discussed and used to explain the day-to-day variation of the equatorial anomaly. Moreover the difference of the variations of the foF2 caused by the ionospheric storm from the TDOEA are found out. The mechanism of the TDOEA is also given.