A receptacle connector has an insulator, multiple contacts, a shell, an insulating bracket, and a detection contact. The shell covers the insulator and the contacts and has a cavity to receive the insulator and the contacts. A detection arm is formed on one of two sidewalls of the shell, which is resilient and able to be deformed by external force and recovered after removal of the external force. The insulating bracket is mounted outside of one of the sidewalls of the shell and has mounting slot defined in the insulating bracket. The detection contact is mounted in the mounting slot of the insulating bracket and is capable of contacting the detection arm. When a plug connector is inserted into the receptacle connector, the detection arm is bent to contact the detection contact for detecting the existence of the plug connector and activating signal transmission or power supply.