An electrostatic discharge (ESD) clamp circuit is provided. The ESD clamp circuit includes a first resistor, a second resistor, a first transistor, a second transistor, and a third transistor. A clamp device of the ESD clamp circuit is implemented by the third transistor. A parasitic capacitor of the third transistor forms a detection scheme along with the second resistor to detect the ESD. The first resistor, the second resistor, the first transistor, and the second transistor form a feedback scheme to control the third transistor for discharging the ESD current.