The invention discloses a novel millimeter wave sub-sampling DDS frequency mixing fractional frequency division phase-locked loop structure. The structure comprises a buffer, a first sub-sampling phase discriminator PD1, a second sub-sampling phase discriminator PD2, a DDS, a DAC, a multiplier, a voltage and current conversion circuit, a low-pass filter, a first inverter chain F1, a second inverter chain F2, a frequency divider and a voltage-controlled oscillator. Frequency mixing is carried out after sampling output, the required DDS output frequency is greatly reduced, and good linearity andlow power consumption can be achieved while the power consumption is reduced. The structure has the characteristics that the high-resolution characteristic of the DDS output signal frequency is not influenced by a phase-locked loop, the phase-locked loop enables a frequency synthesizer to jump in a wide frequency range in a minimum frequency stepping manner, and the DDS provides the capability ofjumping in a narrow frequency range in a very small frequency stepping manner. Therefore, the broadband frequency conversion speed depends on the loop locking time of the phase-locked loop, and the narrowband frequency conversion speed after loop locking depends on the frequency conversion time of the DDS.