ZrAl3/Al composite fuels (Al-xZr, x=10, 20, 30, 40, 50, 53 wt.%) were prepared by the non-consumable arc-melting technique and close-coupled gas-atomization. In order to study the effects of the zirconium content and the oxygen partial pressure on the thermal properties of composite fuels, X-ray diffraction, scanning electron microscopy, TG-DTA and DSC were used to characterize the composite fuels, respectively. The result shows that the addition of zirconium leads to the formation of a special structure inside the powder, promoting the oxidation of ZrAl3/Al composite fuels. Besides, non-selective oxidation of ZrAl3 played an important role in promoting the oxidation process. The oxygen bomb experiment was conducted to evaluate the combustion performance of ZrAl3/Al composite fuels. Oxygen bomb experiments show that the gravimetric combustion enthalpy of the composite fuels decreases linearly with the increase of zirconium content, and increases with the increase of oxygen partial pressure. However, the volumetric combustion enthalpy decreases first and then increases with the increase of zirconium content, and shows a general upward trend when the partial pressure of oxygen reaches 2.5 MPa or more. The pressure curve indicates that the Al-53Zr composite fuels have the maximum pressure propagation rate (dP/dt)(max) (which characterizes the maximum flame propagation rate and higher energy releasing rates) in the prepared series of composite fuels. The study demonstrates a complete combustion of ZrAl3/Al composite fuels under high pressure. ZrAl3/Al composite fuels could be considered as a very promising energetic additive in the field of new-energetic material.