Abstract: The computerized ionospheric tomography (CIT) is a serious under-determined ill-posed inverse problem. The limited-angle geometry and sparse receivers lead incomplete information in measurements, which affect the precision of the CIT imaging, especially in the vertical dimension, the error could reach more than 50km. In order to resolve the problem, this paper puts forward a new method by combining vertical, oblique sounding data and top sounding data with the total electron content (TEC) from an assumed tri-band beacon. This method has two merits, firstly, the initial profile for the iteration is specified by actual vertical, which deviates from the actual electron density distribution and is smaller than those calculated only from models. Secondly, the ground base equipments have high vertical resolution, which make up the disadvantage of the tri-band beacon and improve the precision of the CIT imaging.