An enable circuit suitable for negative voltage output belongs to the technical field of power electronics and comprises an enable signal processing module, an external enable and gate module and a logic module. In case of a great deviation occurred to internal bias current, the external enable and gate module replaces the internal bias current with external bias current so as to provide global deviation current, and provides a forced enable signal; the enable signal processing module converts voltage difference information between an enable signal and an enable signal reference ground into current information; current information is compared with global deviation current to obtain information of whether to enable. The enable signal processing module also has a delaying function and can gain improved interference resistance; the logic module processes output signals from the enable signal processing module and the external enable and gate module so as to generate a global enable signalfor negative voltage outputting. The enable circuit herein is suitable for a wide voltage range of enable signal, can output negative voltage, and can provide external forced enabling.