A new method of preparing nanoparticles by pulsed-laser ablation of a tiny wire was reported, and pure maghemite (γ-Fe_2O_3) nanoparticles were synthesized by this method in a mixed gas flux of N_2 and O_2 at atmospheric pressure. The obtained γ-Fe_2O_3 nanopartiles were in the range of 5 to 80 nm in diameter and largely spherical in shape. Structural characteristics and morphologies of the nanoparticles were characterized by XRD and TEM, respectively. Moreover, magnetic properties of the obtained γ-Fe_2O_3 nanopartiles in the temperature range of 300 to 773 K were investigated. The experimental results demonstrate that the squareness value of the hysteresis loop decreases with increasing temperature. Both the coercivity and the saturation magnetization of the γ-Fe_2O_3 nanoparticles show a constantly decreasing trend with increasing temperature up to the occurrence of the transformation from γ-Fe_2O_3 to α-Fe_2O_3. Especially, at the temperature of 773 K, the γ-Fe_2O_3 begins to transform to the α-Fe_2O_3 phase and the hysteresis loop becomes unclosed. A new method of preparing nanoparticles by pulsed-laser ablation of a tiny wire was reported, and pure maghemite (γ-Fe_2O_3) nanoparticles were synthesized by this method in a mixed gas flux of N_2 and O_2 at atmospheric pressure. The obtained γ-Fe_2O_3 Structural characteristics and morphologies of the nanoparticles were characterized by XRD and TEM, respectively. Furthermore, magnetic properties of the obtained γ-Fe 2 O 3 nanopartiles in the temperature range of The experimental results demonstrate that the squareness value of the hysteresis loop decreases with increasing temperature. Both the coercivity and the saturation magnetization of the γ-Fe 2 O 3 nanoparticles show a constantly decreasing trend with increasing temperature up to the occurrence of the transformation from γ-Fe 2 O 3 to α-Fe 2 O 3. Especially, at the temperature of 773 K, the γ-Fe 2 O 3 begins t o transform to the α-Fe_2O_3 phase and the hysteresis loop becomes unclosed.