The invention discloses a device and a method for measuring idle noise power of a power line communication network. The device comprises an analog front-end unit, an automatic gain control unit, a frame synchronization unit, a demodulation decoding unit, a main control unit and a sending unit. The analog front-end unit is used for amplifying, filtering and performing analog-to-digital conversion on the received power line carrier signals; the automatic gain control unit is used for performing power measurement and gain control on a signal input by the analog front-end unit; the frame synchronization unit is used for performing frame synchronization, bit synchronization and timing control on a physical layer frame of the power line carrier signal; the demodulation decoding unit is used forperforming frequency domain processing and bit-level processing on the signal input by the frame synchronization unit; the main control unit is used for scheduling the automatic gain control unit, theframe synchronization unit and the demodulation decoding unit; and the sending unit is used for sending signals. The measurement device and the measurement method thereof can improve the measurementaccuracy of the noise power when the power line communication network is idle.