Abstract: Single magnetic domain hexagonal barium ferrite BaFe₁₂O₁₉ particles were synthesized at 850℃ Via Sol-Gel technique. The structure, magnetic properties and morphorlogy of the particles were characterized by X-ray diffraction, vibrating sample magnetometer and scanning electron microscopy. The effect of temperature and heating time on the structure, magnetic properties and morphorlogy of the particles was studied. Higher heating rates favored the formation of plate-like particles. With the increase of the heating time and the heating temperature, the hexagonal barium ferrite BaFe₁₂O₁₉ particles were more uniform, and the crystallinity was more perfect, and the size of the particles increased. Owing to the single magnetic domain of the particles, the specific saturated magnetization and the coercivity were enhanced with the increase of the heating time and the heating temperature. The specific saturated magnetization was 53 A·m²/kg and the coercivity was 277.6×0³ A/m for the sample calcined at 850℃ for 4 h. In comparison, the sample calcined at 1 000℃ for 4 h exhibited a specific saturated magnetization of 59 A·m²/kg and a coercivity of 353.3×10³ A/m. For the samples calcined at 850℃, with the heating time increasing, the specific saturated magnetization increased from 48 A·m²/kg to 56 A·m²/kg, and the coercivities also increased form 211.5×10³ A/m to 357.1×10³ A/m.