The invention provides a phase-locked loop phase difference adjusting device which comprises a phase difference detection module, a data processing module, and a digital-to-analog conversion module. A phase-locked loop inputting clock and a phase-locked loop output clock are connected to the input end of the phase difference detection module, and are used for detecting the phase difference of the input clock and the output clock; the data processing module is connected to the phase difference detection module, converts the detected phase difference data in proportion into DAC_data and outputs the DAC_data; the digital-to-analog conversion module is connected to the data processing module, takes the DAC_data as input data and converts the DAC_data as output currents, and the output currents are used as the input of a phase-locked loop filter. The phase-locked loop phase difference adjusting device is used in cooperation with an existing phase-locked loop, can adjust the phase between the input clock and the output clock dynamically under the situation that the losing lock phenomenon of the phase-locked loop does not occur, and improves synchronism.