The present invention discloses a smart grid sensing device. The smart grid sensing device comprises a central processing unit, a global positioning system connected with the central processing unit, a large-volume data buffer, a temperature sensor, a high-precision analog-digital converter, an induction taking power circuit, a short-range wireless communication module and a long-range wireless communication module. The central processing unit is connected with a digital analog converter which is connected with a crystal oscillator, and the crystal oscillator is connected with the central processing unit. Through adoption of a mode of taking power from power induction current, the smart grid sensing device supplies power to a device with no need for external power source and battery; and the smart grid sensing device is not limited by single-end power supply and is slightly influenced by the factors such as the fluctuation of load, the harmonic wave, the grounding resistance, the fault close angle and the like; and moreover, the original fault transient state information and the opposite end information are effectively utilized in the fault feature extraction, the single-phase earth fault line selection and positioning problems of a small current grounding system are effectively solved.