The invention discloses an all-digital low-level system based on a digital phase-locked loop, and the all-digital low-level system is a closed loop as a whole and is used for controlling the amplitudeand phase information of a high-frequency signal. The closed loop is separated from the two ends of an accelerator cavity and is composed of three main body amplitude-phase control branches which areconnected in parallel. The three main body amplitude-phase control branches which are connected in parallel share one input end ADC and one output end DAC; the ADC input end samples data from an accelerator cavity, the DAC converts a digital signal into an analog signal and outputs the analog signal to the power amplifier, the analog signal is fed into the accelerator cavity through the power amplifier, and the ADC samples from the accelerator cavity to form a closed loop; the closed loop is further connected with a digital phase-locked loop for locking the phases of all signals of the wholesystem to an external reference signal source, the problem that the phases of multiple signals are locked to the same signal source is solved, system interfaces are reduced, the system complexity is reduced, and the system reliability is improved.