With the advent in the development of science and technology in the field of space and atmospheric science in order to obtain accurate result, hence the use of radio occultation technique in the investigation of the amount of electron density and Total Electron Content presence in equatorial region particularly over Thailand. In this research, radio occultation data obtained from UCAR/CDAAC was used to observe daily, monthly, seasonal and the entire year 2013 Ionospheric TEC and electron density variation due to changes and instability of solar activities from time to time. It was observed that TEC was high (ionosphere was more disturbed or violent) in May and spread over a wide range of altitude and summer season has the highest TEC value for the year 2013 which means at this period GNSS measurements was more prone to error. It was noted that ionospheric variations or fluctuations was maximum between 200km and 450km altitude. The results of the study show that ionospheric perturbation effects or irregularities depend on season and solar activity