To address issues such as uneven component distribution and significant variability in ignition performance of B/KNO₃ propellants prepared by traditional mechanical mixing methods， microfluidic technology was employed to achieve in-situ preparation of this propellant. Numerical simulations using FLUENT software optimized droplet formation conditions， employing anhydrous ethanol as the continuous phase and a KNO₃ aqueous solution containing B powder， phenolic resin， and graphene/Fe₂O₃ as the dispersed phase， with an optimal flow rate ratio of 10∶1 between the phases. This approach enabled in-situ recrystallization of KNO₃ and in-situ doping of graphene and Fe₂O₃ via microfluidic techniques. Structural and thermal properties were characterized using SEM， EDS， BET， FTIR， and TG-DSC； thermal decomposition kinetics parameters were calculated via the Kissinger method， and combustion time consistency was verified through parallel combustion tests. Results demonstrated that microfluidically prepared B/KNO₃ propellants exhibited uniform component distribution， smaller particle sizes， a 104.5% increase in specific surface area compared to mechanically mixed samples， and a reduction in average combustion time from 80.67 ms to 64.33 ms （a 20.2% improvement）. The synergistic effect of graphene""s thermal conductivity combined with Fe₂O₃""s catalytic activity significantly lowered the system""s activation energy， primary decomposition onset temperature， and exothermic peak temperature， further accelerating combustion rates. Optimal addition concentrations were determined as 0.8% graphene and 2% Fe₂O₃， reducing the average combustion duration to 50.33 ms.