In this paper, we gain a new extension of well-known Darbo's fixed point theorem in a Banach space. Our results provide several expressions which all are generalizations of Darbo's fixed point theorem. As applications, we obtain some Prešić type extensions of Darbo fixed point theorem which help us in the studying of the existence of solution for a system of functional integral equations in BC(R +). Finally, we provided an example to demonstrate the efficacy of our results