To improve the sensitivity of air pollutants detection, a type of surface plasmon resonance-photonic crystal fiber (SPR-PCF) sensor based on graphene coating is proposed. The sensor adopts a hexagonal double arrangement structure with air holes of different diameters. The outer core of the sensor is coated with gold film, and a layer of graphene material is coated between the gold film and the object to be measured to improve sensitivity. The effects of metal layer thickness, spacing and diameter of air holes, and graphene thickness on the sensitivity of the SPR-PCF sensor were systematically investigated using the finite element method. For a refractive index range of 1.398~1.402, the results show that the sensor exhibits significant surface plasmon resonance effect. Applying the optimal structural parameters obtained by analysis, the sensing performance was almost unaffected by the ambient temperature. The maximum wavelength sensitivity reached 55,000 nm/RIU, and the corresponding refractive index resolution was 1.82×10^-6RIU. Compared with the structure coated with graphene in the same refractive index measurement range, the wavelength sensitivity of the proposed SPR-PCF sensor was 2.86~9.17 times that of the existing typical SPR-PCF sensor, and the refractive index resolution of the former was 0.109~0.349 that of the latter. Therefore, the proposed SPR-PCF sensor has good application prospects in the detection of atmospheric pollutant type and concentration.