Abstract: Dysprosium ferric hydroxide macroaggregates(Dy\|FHMA) is prepared by using Dy 3+ coprecipitation with Fe 2+. The preparation conditions is that the molar radio of Dy 3+ to Fe 2+ is 2/1, the concentration of PVP solution is 16 g/L, and the time in ultrasonic bath is 5 min. Under these conditions, the particles size of Dy\|FHMA is measured by microscope to be in a range of 3～34 μm. The distribution of particles , size can keep unchanged at least 48 h. 165 Dy\|FHMA produced from the irradiation of pre labeled inactive Dy\|FHMA in a miniature neutron reactor compared with 165 Dy\|FHMA via coprecipitation of irradiated 165 Dy(NO\-3)\-3 with FeSO\-4, the result indicates that both methods can get the same size range of particles, although the shape of particles shows small differences. This new preparation method, as a hopeful substitute for the conventional method proposed by literature, would make the loss of radioactivity and the damage to the operator reduced.\;