An electrostatic discharge protection device includes a voltage divider, a resistor, a capacitor, a first primary transistor, a second primary transistor, a first control circuit, and a second control circuit. The voltage divider is coupled between a first system terminal and a second system terminal for providing a voltage. The resistor is coupled to the first system terminal, and the capacitor is coupled to the resistor. The first primary transistor and the second primary transistor are coupled in series between the first system terminal and the second system terminal. The first control circuit turns on the first primary transistor when an electrostatic discharge event occurs according to voltages provided by the voltage divider and the resistor. The second control circuit turns on the second primary transistor when the electrostatic discharge event occurs according to voltages provided by the voltage divider and the first control circuit.