In the short pulse region, the knot surface breakdown is the chief damage that was induced by the electromagnetic pulse to the electronic devices. The power that leads the devices damaged relates with the pulse width. Electrostatic discharge (ESD) is a course with high electric potential and instantaneous large current, and ESD breakdown of the electronic devices is quite similar with it. According to the Wunch-Bell's model theory that appraises pulse width threshold of semiconductor device, combining the Human-body Model (HBM) of ESD, the theoretical formula calculating damage threshold voltage of ESD was derivated. It provides one kind of method to estimate ESD damage threshold in the condition of lacked experimental data.