In this paper, the metal–insulator–metal (MIM) plasmonic directional coupler (PDC) with 45° waveguide bends based on surface plasmon polaritons (SPPs) excitation has been analyzed by the finite-difference time-domain (FDTD) numerical method. Effects of the variations of the coupler length and the metal gap thickness on the output powers and the propagation loss at 1550nm wavelength have been studied. By choosing proper coupler lengths, power splitters with various output power ratios at 1550nm wavelength and multi/demultiplexers, as some applications of the directional couplers have been proposed and their performances have been simulated.