Numerical analysis and comparison of surface plasmon resonance (SPR)-based photonic crystal fiber (PCF) structures are presented. Full vectorial finite-element method (FEM) is employed to model and compare circular, elliptical, and square air hole-based PCF structures. The key propagation features, such as phase matching, sensitivity, resolution, and confinement loss behaviors of proposed structures, are reported. The effects of geometrical and design parameters are discussed and compared thoroughly. It is found that the sensitivity of circular air hole-based structure can reach up to 4200 nm/RIU, and the sensor resolution is 2.4 × 10 − 5 RIU.