The invention relates to the measurement technology field and particularly relates to a current measurement device and method. For a current measurement sensor in the prior art, measurement and power supply functions are separate, two mutual inductors are required in a device set, so the occupation space of online monitoring equipment is made to be relatively large, and production cost is enhanced. The current measurement device comprises an electricity taking unit, an energy supply unit and a measurement unit, wherein the electricity taking unit comprises a current source module, the energy supply unit comprises an electricity taking magnetic core, a current source module, a voltage waveform signal oscillograph module, a current waveform signal oscillograph module and a rectifier bridge module, the measurement unit comprises a signal conditioning and amplification module and a micro-control module. The measurement device is advantaged in that design complexity is substantially simplified, the volume and weight can be reduced, and production cost is saved. The invention further relates to the current measurement method.