This study investigates water-soluble ions in the sized particles (particularly Aitken nuclei mode (dp ≤ 0.1 µm, PM0.1)/accumulation mode (0.1 < dp ≤ 1.0 µm, PM0.1–1.0)) collected using a MOUDI sampler in the YanShuei area of southern Taiwan during a beehive fireworks display. The results indicate that the PM2.5 and PM10 concentrations (437 µg/m3 and 572 µg/m3, respectively) at the leeward sampling site are 12.5 and 4.6 times higher than the corresponding national standards of daily mean values (35 and 125 µg/m3, respectively) during the beehive fireworks display. Closely examining PM accumulation fractions reveals that the accumulation mode particles dominate in the sized collected particles during the beehive fireworks display. Additionally, the K+ concentrations in PM1.0, PM2.5, and PM2.5–10 are 317, 349, and 249 times higher than those of its background value, while those of Cl– are 91, 64, and 6.9 times greater than those of its background value. For ultrafine particles, the D/B (During the beehive fireworks display/Background) values of particle-bound Cl–, K+, and Mg2+ increase significantly during the beehive fireworks display at the leeward sampling site. Moreover, the maxima D/B value of K+ is 196 in the 0.1–0.18 mm size range, revealing that the beehive firework aerosols are rich in Cl–, K+, and Mg2+ ions.