Based on the coupling analysis of the optical Tamm states in the photonic crystal, a refractive index sensing structure containing metal inset layer is proposed. The formation mechanism of optical Tamm state is analyzed and the suitable thickness of the metal is chosen to realize the coupling of two optical Tamm states. The relationship model between the reflection peak wavelength and the refractive index of the sample solution is established, and its refractive index sensing characteristics are discussed. Through the discussion of the periodicity and the incident angle of the photonic crystal, it shows that the full width at half maximum (FWHM) can be reduced by increasing the periodicity (or the incident angle), which can improve the sensitivity of the sensor and the resolution of the refractive index obviously. The ethylene glycol is adopted as the sample detected, the sensitivity of the refractive index sensing structure is about 445.45 nm/RIU, and the quality factor (Q value) can attain to 1259.45. The sensor structure has several advantages such as simple preparation and compact structure, which can provide some theoretical references for the design of high Q value and high sensitivity refractive index sensors.