Abstract: In this paper some proplems in using differential Doppler data to calculate TECby means of the minimum curvature method are discussed and analysed, and the procedure to solve the problems is also given. Using the procedure processed the NNSSsatellite Doppler frequency shift data obtained in Lintong and Beijing on August and September 1989, by the MX1502 receiver, and get the distribution curves of the TEC. From the curves some interesting results about spatial and temperal features of the equatorial anomaly during high solar activity years, expecially during the solar great proton event on 13 August 1989, are found.