Abstract: The paper investigates the variation of the f_oF₂ of five ionospheric stations in the northern hemisphere near 120°E.The motion rules of the equatorial anomaly's northern crest is found as follows: (1) The time sector from sunrise to "the sun right overhead",the crest is in equatorward motion,in the afternoon it moves back toward the pole.(2) The reverse time of the crest motion depends on the smallest zenith angle and on solar cycle.(3) The poleward motion is dominated mainly by ionization's transport processes,the equatorward motion is dominated mainly by the photo-ionizadon processes.(4) The position of the northern crest ionospheric equatorial anomaly near 120°E is on Hainan in the morning,nearly on Guangzhou in the afternoon.