The presented research discusses the analysis of a triangular-shaped three-dimensional nano-plasmonic coupler. The coupler's intended purpose is to couple two waveguides: silicon and metal-insulator-metal (MIM), where gold has been utilized to clad the MIM waveguide. One of the most important metrics for evaluating nano-plasmonic couplers is their coupling efficiency. The study suggests a unique structure with a maximum transmission efficiency of ∼92% at the conventional optical wavelength of 1550 nm to increase efficiency. The optimum dimensions for the proposed triangular coupler were found by methodically adjusting the structural characteristics, which resulted in maximizing the coupling efficiency.