Abstract: Sphene solid solution doped neodymium (Ca_0.86Nd_0.14Ti_0.86Al_0.14SiO₅) was prepared using CaCO₃,Nd₂O₃,TiO₂,SiO₂ and Al₂O₃ as raw materials by solidreaction. The chemical stability of sphene solid solution doped Nd by the coupling effect of thermodynamics-hydrodynamics-mechanics-chemistry (THMC) was investigated by the means of product consistency test (PCT), X-ray diffraction (XRD), scanning electron microscope (SEM), inductively coupled plasma atomic emission spectrometry (ICP-OES) and so on. The results indicate that Ca_0.86Nd_0.14Ti_0.86Al_0.14SiO₅ solid solution has good chemical stability by the coupling effect of the pH＝5.9, 150-200 ℃ and 0.476-1.554 MPa; the pH value and temperature (pressure) have no significant impact on the normalized leach rate of Si⁴⁺, Al³⁺ and Nd³⁺; the anti-leaching property of Ca²⁺ at 200 ℃ (1.554 MPa) is better than that at 150 ℃; early in the immersion, the anti-leaching property of Ca²⁺ in pH=9 is better than that in pH＝5 and 7, late in the immersion, the anti-leaching property of Ca²⁺ in solid solution is converge in the three solution; the antileaching property of Ti⁴⁺ in pH＝9 is better than that in pH＝5 and 7.