In this research, we design a plasmonic refractive index sensor and examine it numerically, using transparency, refractive index, sensitivity, FOM fit shape and Q quality factor, to optimize and improve performance quality. We will be. To design the structure of this sensor, we use two plasmonic waveguides, a cavity, two rings and two teeth. The resonant wavelengths and refractive index of the resonators are investigated and simulated by the finite difference time domain (FDTD) method, and we draw the obtained diagrams using MATLAB software. After completing the sensor design, due to the fact that the amplifiers are very sensitive to changes in the refractive index, so by changing the refractive index and changing the dimensions of the structure, we can weaken or strengthen the passage coefficient in the resonant modes. These plasmonic sensors with a simple frame and high optical resolution can be used to measure refractive index in the medical, chemical and food industries.