System used for detecting power voltage

The invention provides a system used for detecting power voltage. The system comprises a reference signal generation device, a comparison device and an output buffer device. The reference signal generation device is used for generating a first reference signal and a second reference signal, both of which vary with to-be-tested power voltage. The comparison device is used for comparing the first reference signal with the second reference signal and generating a comparison result signal. The output buffer device is used for generating an output reference signal on the basis of the comparison result signal. Theoutput reference signal reflects a voltage mode of the to-be-tested power voltage. The detection of the power voltage is not affected by impact of deviation of the power voltage apart from deviation of process temperature. The influence upon detection of the power voltage is little. Therefore, accurate detection results are outputted at all process corners.