Long-span pedestrian suspension bridges generally exhibit low stiffness, small damping, and lightweight structural characteristics, making them susceptible to wind-induced vibrations that affect pedestrian comfort and structural safety. However, systematic studies on their aerodynamic stability remain limited. To investigate the aerodynamic characteristics and influencing factors, wind tunnel tests were conducted based on a pedestrian suspension bridge under construction in a mountainous scenic area. The aerodynamic responses corresponding to the first symmetric and antisymmetric modes were measured. Results indicate that the bridge shows insufficient flutter stability at attack angles of 0°, ±3°, and +5°. To improve aerodynamic performance, three optimization measures were proposed and validated: installation of stabilizer plates, adjustment of railing porosity, and a combination of both. The tests show that either stabilizer plates or unconventional enclosed railings alone can improve the critical flutter wind speed at specific attack angles but may reduce it at opposite angles, indicating complementary aerodynamic effects. Further analysis revealed that their proper combination significantly enhances aerodynamic stability. Two optimized configurations were determined: (1) two 1.5 cm stabilizer plates installed below girders #2 and #6 with 7 mm grid-pattern railings, and (2) two 2 cm stabilizer plates with 7 mm star-pattern railings. Both configurations satisfy the stability requirements for flutter and vortex-induced vibration.