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. The numerical simulation was carried out by FLUENT software to optimize the droplet formation conditions， and the optimal flow velocity ratio of continuous phase and dispersed phase was determined to be 10∶1. Under this process， the in-situ recrystallization of KNO₃ and the in-situ doping of graphene oxide and Fe₂O₃ were realized with the help of microfluidic technology， using absolute ethanol as the continuous phase and KNO₃ aqueous solution containing boron powder （b）， phenolic resin （PF） and graphene oxide/Fe₂O₃ as the dispersed phase. 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 the thermal conductivity of graphene oxide combined with the catalytic activity of Fe₂O₃ significantly lowered the activation energy of the system， primary decomposition onset temperature， and exothermic peak temperature， further accelerating combustion rates. Optimal addition concentrations were determined as 0.8% graphene oxide and 2% Fe₂O₃， reducing the average combustion duration to 50.33 ms.