Mn-Zn ferrites(Mn_(1-x)Zn_xFe_2O_4)with different compositions were prepared by the coprecipitation method,and the influences of such synthesis conditions as pH value,composition and volume ratio(R)of the mixed solution and NH_4HCO_3 solution on their microstructures and magnetic properties were discussed.The samples were characterized by X-ray diffraction(XRD)and magneti-zation measurement instrument.Lattice parameters and average crystalline size of the synthesized materials were calculated from the corresponding XRD patterns with the related software Jade.5.For samples of different pH values,only one phase was found when pH values were 7.0,8.0 and 9.0.The sample with pH value of 7.0 exhibited the highest saturation magnetic induction,the lowest coercive force,and crystallized best.For samples of different R values with pH value of 7.0,only one phase was observed in all samples,and the sample with R value of 2.3 exhibited the highest saturation magnetic induction and the lowest coercive force.The composition has mainly afected the magnetic properties,and the saturation magnetic induction increases with the increase of the content of Zn(x),but decreases when x is beyond 0.6.The trend of coercive force is on the contrary.However,no magnetism is ex-hibited when the x value is up to 0.8.