The invention provides an electrical quantity based anti-islanding device. The device comprises a mother board module, a secondary voltage and current acquisition conversion module, an input signal acquisition module, a control processing module, an output drive module, an alarm signal output module, a display module and a power supply module. The voltage and current acquisition conversion module, the input signal acquisition module, the control processing module, the output drive module, the alarm signal output module and the display module are in signal electrical connection with the control processing module respectively. The control processing module comprises an analog/digital (AD) conversion chip, a field programmable gate array (FPGA) chip, a central processing unit (CPU) and an optical fiber communication interface. According to the device and an operation method, islanding can be determined rapidly and reliably, small distributed power supplies can be disconnected rapidly, and accordingly, the safety of maintainers and relevant equipment is effectively guaranteed; the problem of non-detection zones during low system exchange power of prior passive detection methods is solved through a frequency difference energy integral method; the device is simple in structure, low in cost and high in adaptability.