Based on the preparation technology of non-deuterated HMX using paraformaldehyde as raw material, deuterated octagon(β-HMX-d₈) was successfully synthesized with a total yield of 58.5% from deuterated paraformaldehyde. The β-HMX-d₈ was obtained via recrystallization method using acetone as the crystal transformation solvent. The intermediates and final products were characterized by ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared(FT-IR) spectroscopy, ¹H-nuclear magnetic resonance(¹H NMR) spectroscopy, ¹³C-nuclear magnetic resonance(¹³C NMR) spectroscopy, thermogravimetry-derivative thermogravimetry (TG-DTG), differential scanning calorimetry(DSC), or x-ray powder diffraction(XRD). The deuterated ratio of systhesized β-HMX-d₈ is 99.75% measured by NMR method with maleic anhydride as an internal standard. The purity of HMX-d₈ is 99.27% determined by HPLC via area normalization method.