An electrostatic discharge (ESD) protection circuit including a monitoring unit, a main discharge transistor, and an auxiliary discharge transistor is provided herein. The monitoring unit is configured to detect an electrostatic pulse caused by accumulation of electrostatic charges. The main discharge transistor and the auxiliary discharge transistor are configured discharge the electrostatic charges to ground end after the electrostatic pulse is detected. A first section of a power supply metal line is coupled to the main discharge transistor and the auxiliary discharge transistor, a third section of the power supply metal line is coupled to an internal circuit protected by the ESD protection circuit, and a second section of the power supply metal line couples the first section to the third section. The power supply metal line includes an angle that is less than 180 degrees at a contact position between the second section and the first section.