An electrical plug connector and an electrical receptacle connector adapted to be mated with the electrical plug connector are provided. The electrical receptacle connector includes an insulated housing integrally formed as a whole and a plurality of receptacle terminals. Based on a supporting arm of a first side arm of the receptacle terminal, when the plug terminal is abutted against the first side arm, the supporting arm is abutted against an abutting surface of the electrical receptacle connector for supporting the first side arm and improving the structural strength of the first side arm. Therefore, the first side arm can be prevented from being deformed or broken. In addition, based on a supporting segment of a second side arm of the receptacle terminal, the flexibility of second side arm can be improved and the structural strength of the second side arm can be enhanced.