An electrical receptacle connector includes a terminal module assembly and a grounding collar thereon. The terminal module assembly includes the front mating tongue, the rear body, and the step structure therebetween, and the corresponding contacts. The contacts are secured to the body with contacting sections exposed upon the mating tongue. The grounding collar includes the grounding regions located on two opposite upper and lower surfaces of the step structure. The front edge area of the grounding region adjacent to the front edge area, forms a notch so as to leave a space to allow the spring finger of the corresponding interior grounding plate of the plug connector to first slide upon the step structure and successively contact the grounding region of the grounding collar of the receptacle connector.