The invention discloses an ad-hoc network sensing device for an earth wave of a switch cabinet. The device comprises a transient earth voltage sensor, a band-pass filter, an amplifier, a down-frequency detector, an A/D converter, an analysis control module, a storage module, a wireless transmission module and a real-time clock module; the transient earth voltage sensor is used for detecting a partial discharge signal of the earth wave and outputting the partial discharge signal to the band-pass filter; the band-pass filter, the amplifier, the down-frequency detector and the A/D converter are connected in sequence and are used for transmitting a digital signal to the analysis control module, the analysis control module is used for extracting characteristic information of the partial discharge signal and preliminarily evaluating the insulation state of the switch cabinet, the storage module is used for storing the detection data, the wireless transmission module is used for transmittingthe detection data and receiving a control instruction issued by a monitoring terminal, and the real-time clock module is used for regularly starting the wireless transmission module to send the detection data. According to the device, the insulation state of the switch cabinet is preliminarily evaluated, manpower and material resources are saved, the detection efficiency is improved, and the subjectivity of manual detection is avoided.