Energetic particles have been used in solid propellant to increase the energy content, but for liquid fuel, the addition of such particles is still challenging because of severe particle precipitation. Here we demonstrate the possibility of adding surface-modified boron nanoparticles (NPs) in jet fuel JP-10. Trioctylphosphine oxide is very effective to stabilize NPs by inhibiting the contact and agglomeration. After 6 weeks, 12.7 wt% NPs are still dispersed in fuel, which increases the density and volumetric energy from 0.93 g/mL and 39.4 MJ/L to 0.98 g/mL and 43.4 MJ/L, respectively. The suspension flows freely like liquid fuel and has relatively low viscosity at low temperature.