A GNSS radio occultation detector provided by the present invention comprises a positioning antenna, an occultation reception antenna, a radio frequency unit and an occultation processing unit. The radio frequency unit is used to carry out the amplification and radio frequency filtering processing on the GNSS signals received by the positioning antenna, an atmosphere occultation antenna and an ionized layer occultation antenna and then input a generated radio frequency signal to the occultation processing unit, the occultation processing unit carries out the signal capture and tracking according to the received radio frequency signal and utilizes the signal after tracking to calculate the satellite position, the speed information and the carrier phases of the GNSS signals, and the positioning antenna, the atmosphere occultation antenna and the ionized layer occultation antenna all adopt the double-frequency laminated micro-strip antennas to separately cover the high and low working frequency bands of a GPS and a BDS in a GNSS. The GNSS radio occultation detector of the present invention realizes the compatibility of the GPS and the BDS, and enables the detection capability to be improved.