A new kind of surface plasmon resonance (SPR) sensor based on hollow-core fiber structure is proposed. The performance of the designed sensor is theoretically analyzed with a ray model theory. Sensors with different silver film thicknesses are fabricated. An online testing system is set up and the SPR spectra of liquids filled in the fiber core with different refractive indices are obtained with the sensors of different silver layer thicknesses. Sensitivity and detection accuracy of the sensors are investigated both theoretically and experimentally. The designed sensor is a kind of fiber SPR sensor with high sensitivity, which can detect the high refractive index liquid medium in real time. It can make up the deficiency of the conventional fiber SPR sensor in a certain range and open up a new application field for hollow-core fiber.