The invention discloses a coaxial dielectric oscillator. A signal output by the reference source is transmitted to the analog phase discriminator; an analog phase discriminator carries out phase comparison on a reference source signal and a feedback signal of the power coupler. The analog phase discriminator transmits voltage generated by the phase difference to the loop filter; the loop filter transmits the filtered signal to the coaxial medium voltage-controlled oscillator; the coaxial medium voltage-controlled oscillator carries out frequency adjustment on an input signal and then transmitsthe input signal to the power coupler, the power coupler feeds back a signal to the analog phase discriminator, outputs a required frequency signal selected from a generated frequency signal throughthe band-pass filter and then transmits the required frequency signal to the power amplifier, and the power amplifier filters redundant stray and harmonic waves through the output filter and then outputs the signal to the outside. The microwave frequency source has the advantages of high frequency purity, high frequency stability, low phase noise and high anti-seismic property.