Optical fiber based surface plasmon resonance (SPR) sensor, with small size and low cost, has been widely applied in biochemical, medical diagnostics and environmental monitoring due to its high sensitivity and real-time remote sensing. It is of great help for the application of fiber optic SPR sensor to understand its structure and the characteristics of the sensing data. This chapter first introduces the key technology for fabricating fiber optic SPR sensor, then introduces the influence of metal oxide film on the sensing performance of fiber optic SPR sensors, and finally introduces the data processing method for SPR data.