Abstract: La³⁺ doped cobalt ferrite CoFe_2-xLa_xO₄(x=0, 0.05, 0.10, 0.20, 0.40, 0.80) powders were prepared via hydrothermal method. The influence of doped La³⁺ content on the structures, morphologies and magnetic properties of cobalt ferrites was studied by X-ray diffractionmeter(XRD), scanning electron microscope (SEM) and vibrating sample magnetometer(VSM). The results show that with the increase of doped La³⁺ content, XRD diffraction peak intensities of as-prepared cobalt ferrites are reduced,and the second phase appears at x=0.10. Agglomeration of particles is significantly alleviated at x≥0.10. The saturation magnetization decreases gradually from 63.856 (A·m²)/kg to 25.539 (A·m²)/kg, while the coercivity firstly decreases from 71.14 kA/m to 38.18 kA/m and then increases to 160.45 kA/m.