We adopt precipitation to prepare the nanometer CuO and coat it on boron particles of micro- and nano-size. The morphology and coating result of B/CuO nanocomposite thermite were characterized using different techniques, such as scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The results indicated that the boron particles were coated completely by nanocomposite CuO and well distributed. The B/CuO nanocomposite thermite reaction process was tested by thermogravimetric/differential scanning calorimetry. The obtained reaction temperature of B/CuO particles is about 116.86° lower than that of boron particles. The B/CuO thermite and boron powder were added to Mg/PTFE propellant to be measured for their respective combustion performance. The results showed that the B/CuO-Mg/PTFE propellant burning rate increased by 12.87%, mass burning rate by 13.48%, and combustion temperature increased by 56.3° compared to the B-Mg/PTFE propellant. The above results indicate that the CuO coating of boron particles increases the combustion performance of propellant compared with uncoated particles.