<p>In the near-infrared band, this paper proposes a highly sensitive all-dielectric metasurface refractive index sensor structure based on the Fano resonance, three performance index parameters of the sensor structure, the sensitivity, the figure of merit, and Q-factor can reach high values at the same time. In this paper, the transmission characteristics of the structure are simulated and analysed using the Finite difference time domain method. Firstly, the cause of the Fano resonance of the structure is theoretically explained, and at the same time the theoretical curves are fitted to the simulation curves. Secondly, the formation mechanism of this Fano resonance was further analysed through the electric field phase diagram, and the influence of the geometrical parameters of the structure on the sensing performance of the structure was investigated, while the geometrical parameters of the structure were optimised. Finally, the sensitivity of the structure was calculated to be as high as 1150 nm/RIU, the figure of merit of 1.917 × 10⁴ and Q-factor of 3.365 × 10⁴ under the optimal structural geometrical parameters, It can be seen that the three performance index parameters of sensitivity, the figure of merit and Q-factor of the structure can reach high values at the same time, and the structure has superior sensing performance. In the near-infrared band, this structure can provide an effective way to improve the performance of all-dielectric metasurface refractive index sensors.</p>