Aiming at the issues such as measurement ability limitation caused by the mismatch between the test probe and the radome under test, as well as the traditional calibration methods apply only for a particular single operating frequency, one kind of radome electrical thickness reflection test probe is proposed innovatively by use of magic-T and half-star cross section prism. By which, the mismatch suppression can be up to 30 dB within 8 ~ 12 GHz full frequency range of X band, and the linearity of the phase mapping between the test signal and insertion phase difference of radome is optimized, and with no calibration required. Using this probe, the reflection test signal can be easily converted into transmission signal, the thickness information of the radome can be obtained by simple phase comparison, and the probe can be used at different operating frequencies at same time.