Abstract: The synroc form of compounding minerals of zirconolite and sphene doped neodymium was prepared by using zircon, calcium carbonate, titanium dioxide, alumina, neodymium oxide as raw materials and solid phase reaction. The chemical durability of synroc form was researched by means of X-ray diffraction (XRD), backscattering scanning electron microscopy (BSE), energy dispersive spectroscopy (EDS), fluorescence spectrum (FS) and so on. The results indicate that the compounding minerals of zirconolite and sphene can dissolve commendably neodymium, and its synroc form has a good chemical durability. The unitary average leaching rates of neodymium of sample CZ15-1260, CZA15-1260 and CA15-1260 are 1.82×10^-4、1.38×10^-4、1.48×10^-4g•m^-2•d^-1, respectively at 90 ℃, the 42nd day. The better sintering temperature of synroc form is 1 260 ℃.