The invention provides a Ku / Ka two-waveband transmitting-receiving share feed source, which comprises a Ku waveband transmitting-receiving system and a Ka waveband transmitting-receiving system, wherein the Ku waveband transmitting-receiving system comprises a Ku radiation end, a stepped choke ring, a coaxial connecting piece, a Ku waveband coaxial orthomode coupler and a Ku waveband receiving-end filter which are connected in sequence; the Ka waveband transmitting-receiving system and the Ku waveband transmitting-receiving system are nested coaxially; and the Ka waveband transmitting-receiving system comprises a dielectric rod structure, a dielectric circular polarizer, a Ka waveband orthomode coupler and a Ka waveband receiving-end filter which are connected in sequence. According to the Ku / Ka two-waveband transmitting-receiving share feed source provided by the invention, a Ku wave receiving-end standing wave is less than 1.4, the cross polarization is less than -30dB, a transmitting-end standing wave is less than 1.3, the cross polarization is less than -23dB, the transmitting-receiving isolation is less than -110dB, a Ka wave receiving-end standing wave is less than 1.8, a transmitting-end standing wave is less than 1.7, the axial ratio is less than 1.8, and the transmitting-receiving isolation is less than -82dB.