The present disclosure illustrates an under voltage lockout circuit in which a band gap circuit includes two current input terminals for generating a first current associated with band gap, an amplifier includes two inputs terminal coupled to the two current input terminal, and an output terminal configured to output an error-amplified signal, a terminal of a control device is coupled with a voltage source, and a control terminal of the control device receives the error-amplified signal, a voltage divider is coupled between current input terminals and other terminal of the control device, a comparator receiving a lockout voltage and outputting an under voltage lockout signal, a current mirror circuit is coupled to the first input terminal of the comparator and the band gap circuit, and configured to generate a second current mirroring from the first current.