In multi-voltage island SoC, power management is one of the most important fields. The current of workload is the firsthand information of power dissipation, so, the current sampling is the first step in the cycle for high accuracy real-time power management. In this paper, we presented a kind of high accuracy current sampling technology. The circuit is based on current mirrors without operation amplifier, and the voltage of power supply can be ultra low. We designed this circuit with 0.18μm CMOS process. It is shown that the accuracy of this circuit can be 99.1% according to the Hspice simulation and power consumption is less than 4mW for workload in 60～1300mA.