Abstract: A Surface Plasmon Resonance (SPR) fiber sensor is disclosed, which comprises an optical fiber member and a plurality of optical fiber sensing units. Each of the plurality of the optical fiber sensing units comprises a cladding layer, a core layer, and a groove, and the plurality of the optical fiber sensing units is arranged into a cascade form matrix. In each of the optical fiber sensing units, the cladding layer is located at the periphery of the core layer, and the maximum depth of the groove is larger than the thickness of the cladding layer. An SPR sensing apparatus is also disclosed, which includes a light source, an optical signal detector, a plurality of fibers, and a plurality optical fiber sensing units. Besides, the optical fiber sensing units, the light source, and the optical signal detector are connected with each other through the plurality of fibers.