Aiming at two kinds of typical optical fiber sensor based on SPR effect, which are traditional multimode optical fiber sensor coated with metal film whose cladding is corrosion, and a novel single-mode optical fiber grating sensor coated with metal film, SPR theoretical model and processing method were presented. First of all, according to the structural characteristics of traditional fiber SPR sensor, using the theory of plate SPR effect, reflection spectra of this sensor were given. Meanwhile, it is pointed out and proved that thin film optical theory and theory of SPR are equivalent in the flat structure. Secondly, according to the structure characteristics of novel SPR fiber grating sensor based on mode coupled theory, combined with the feature of SPW mode, the theory processing method of SPR in fiber grating was put forward, the transmission spectra of triple-cladding LPFG coated with gold film were given. Finally, the comparative analysis on the sensing characteristic of two kinds of typical optical fiber sensor based on the SPR effect was carried out, and the results show that two kinds of structure have high resolution of environment refractive index, but the resolution novel optical fiber grating SPR sensor is higher 3 orders of magnitude than that of traditional fiber SPR sensor.