The relative total electron content （TEC） is obtained through the combination of COSMIC radio occultation ionospheric measurements L1 and L2 phase. The TEC data are then calibrated by non-occultation observation data on the auxiliary side to remove portion of TEC above the LEO orbit altitude. The electron density profile can be retrieved from TEC by Abel integral transformation，with a spherically symmetric assumption of electron density and an approximation of signal straight-line propagation. The computation standard deviation of F2-layer critical frequency f0F2 is about 059 MHz，and the standard deviation of F2-layer peak altitude hmF2 is about 3308 km，as through comparing 4903 COSMIC ionospheric occultation profiles with those from ionosonde stations，of which the longtitude deviations are less than 10°，the latitude deviations are less than 2°.