The Kuramoto model has been studied to investigate the synchronization behavior of coupled oscillators. The classical Kuramoto model assumes that the interactions between oscillators are simultaneous. However, in the real-world systems, the interactions such as chemical reactions, signal transmissions, etc usually take a small time to react. Hence the consideration of time-delay effect is natural and inevitable in the large coupled systems. In this talk, we shall consider the Kuramoto model with time-delayed interaction. We will present a theoretical result for unconditional frequency synchronization when the number of oscillators is 3.