Abstract: To enhance the pressure sensitivity of side-hole fiber Bragg grating sensors, an enhanced side-hole sensitization structure was designed. A pressure sensor model based on the sensitization structure was established using finite element analysis, and the influence of structural parameters on pressure sensitivity was investigated through simulation. By employing response surface methodology for optimal design, a sensor prototype was fabricated using polyurethane material, and its performance was experimentally validated. Results indicate that the designed sensor achieves a pressure sensitivity of 202.41 pm/MPa and a temperature sensitivity of 34.627 pm/℃, representing improvements of 18 times and 3 times, respectively, compared to sensors without the sensitization structure. Furthermore, to address the harsh downhole environment, a protective structure for the sensor was designed and its feasibility was verified. Combining theoretical modeling, numerical simulation, and experimental validation, this study proposes an efficient and feasible sensitization design strategy, which significantly improves the performance of side-hole fiber Bragg grating sensors and provides a novel approach for highly sensitive downhole temperature and pressure composite measurements.