An ESD protection circuit has a merged triggering mechanism. The ESD protection circuit comprises: an ESD detection circuit, for detecting an ESD voltage to generate a control signal; a first type ESD protection device, for outputting a first trigger current; a second type ESD protection device, for receiving a second trigger current; and a trigger circuit, for constituting a conductive path according to the control signal, such that the trigger circuit can receive the first trigger current from the first type ESD protection device and outputs the second trigger current to the second type ESD protection device.