Abstract: The nano-sized ferrite magnetic particles were prepared by chemical precipitation. The properties were investigated by VSM. And the size, appearance and magnetism of Fe_3O_4 nanoparticles charaterized using TEM. The results show that the nagnetic particles have the strongest magnetic properties under the conditions of Y (0.25,)temperatare 80 ℃,heating time 120 min and the ration of surfacant n 0.6.Additionally,the average diameter of partides is about 10 nm with the almost same size.