A fiber-optic surface plasmon resonance sensor (SPR) based on tapered structure probe is studied. The incentive mode of tapered probe calculated by finite-difference time-domain method serves as design references, and the tapered structure of sensor probe fabricated by polishing and grinding at the end of a fiber is similar to Kretschmann prism SPR model, which can realize the modulation of SPR wave. The results show that in the refractive index detection range from 1.3330 to 1.4215, tapered structure FO-SPR sensor has a sensitivity of 1-6 times higher than common FO-SPR sensor and it still keeps a limiting resolution level of 10-5 RIU. The designed tapered structure SPR sensor, which has the advantages of tapered incentive mode, design flexibility, user practical applicability, simple preparation process, a relatively small sample need, and high stability, will fulfill different environment and measuring conditions of biochemical testing and environment monitoring.