Abstract: Sol-gel synthesis of Ni_0.24Cu_0.2Zn_0.56-xCo_xFe₂O₄（x =0.1,0.2,0.3,0.4） is A site doped. Divalent cobalt ions replace divalent zinc ions of B site. According to the XRD spectra of the（311）,（220）,（511）,（440）,（2 22）,（400） and（422） peak,the diffraction peaks show that the structure of the samples is only spinel ferrite. The character of temperature and magnetic susceptibility indicates that the compound is ferromagnetic. The paramagnetic curie temperature of Al（x = 0.1）,A2（x = 0.2） sample are 580 K and 670 K,this temperature can be calculated out by measuring the magnetic susceptibility to study the magnetic exchange interaction. Hysteresis loop shows coercivity（H_c） and remanent magnetization（M_r） increase with the change of doping. This may be that the magnetic anisotropy constant changing with the particle size domain wall movement caused.