A protection device for detecting electricity is composed of a control unit, a set of input ends for sampling, a display unit, an acoustic signal generating unit, and a power unit. The aforementioned control unit includes a microprocessor (CPU), a clock pulse wave generator, a first memory, a second memory, an input/output port, and a timer. The microprocessor processes defects in sampled electrical data, such as voltage and current, to display power consumed and accumulated time of use, such that a user can be aware of the electricity information at any time for preparation. The sampled data are compared with each setting value pre-stored in the second memory, and if any one of the data exceeds the setting value, the microprocessor will output a warning signal or shut down the power, to maintain safety.