To address the problems of irregular morphology and poor mechanical properties of conventional hexanitrostilbene （HNS） crystals， HNS/F₂₆₀₄ microspheres were fabricated via microfluidic technology. By combining Brazilian splitting tests with finite element simulations， the mechanical properties and enhancement mechanism of the as-prepared microspheres were systematically investigated.The results show that HNS/F₂₆₀₄ microspheres with good sphericity and smooth surfaces can be obtained when the dispersed phase flow rate is 0.05 mL·min^-1， the continuous phase flow rate is 2.0 mL·min^-1 （flow rate ratio of 1∶40）， and the collection temperature is 60 ℃. The microspheres retain the original crystalline structure of HNS， while their peak thermal decomposition temperature is 4.6 ℃ lower than that of pure HNS.Brazilian splitting tests indicate that the pure HNS pellet has a peak load of 0.0065 kN and exhibits brittle fracture characteristics； in contrast， the peak load of the HNS/F₂₆₀₄ microsphere pellet increases to 0.072 kN， and its post-peak stress-displacement curve shows multi-stage attenuation， reflecting a transition to ductile fracture. The crack propagation morphology obtained from finite element simulations is in good agreement with the experimental fracture features. The HNS/F₂₆₀₄ composite microspheres prepared by microfluidic technology exhibit a remarkable toughening effect.