A high resonance peak in the spectral response enables a highly sensitive mechanism for refractive index monitoring, enabling accurate detection of environmental changes. In this work, a new plasmonic structure that incorporates two periodic silver nanorods into a metal–insulator-metal (MIM) waveguide are proposed. Dual periodic silver nanorods in MIM waveguide form the basis of the innovative and straightforward plasmonic structure introduced by the suggested design, which has never been described before. Due to the periodic manipulation of silver nanorods, this arrangement offers a high-quality factor resonance and remarkable sensing capability, all while being tiny and straightforward to fabricate. A high-transmission resonance mode that is highly sensitive to the surrounding medium’s refractive index is supported by the cavity produced between these nanorods. The performance of this design using finite element method ($\text{FEM}$) simulations was examined, showing plasmon-induced transparency ($\text{PIT}$) effects and notable improvements in refractive index sensitivity. The sensor is comparable to the most sophisticated plasmonic sensors on the literature with a sensitivity of $1780\text{nm}\mathrm{/}\text{RIU}$. Additionally, the suggested design achieves an exceptional Quality factor ($\text{Q}-\text{factor}$) of 1537.96 and a Figure of merit ($\text{FOM}$) of 1537.39 $RI{U}^{-1}$. A wide range of refractive index (RI) sensing applications could benefit from the sensor’s high performance and straightforward production procedure.