Gallium nitride materials, due to their excellent electrical properties and irradiation resistance, are expected to be used in future space electronics systems where electronic devices are composed of different amounts of Al _xGa _1–xN materials. However, most of their displacement damage studies currently focus on GaN materials, and less on Al _xGa _1–xN materials themselves. The mechanism of displacement damage induced by 10-keV to 300-MeV protons incident on Al _xGa _1–xN materials with different Al content is investigated by binary collision approximation method. The results show that the non-ionization energy loss of Al _xGa _1–xN material decreases with proton energy increasing. When the proton energy is lower than 40 MeV, the non-ionization energy loss becomes larger with the increase of Al content, while the trend is reversed when the proton energy increases. Analyzing the primary knock-on atoms and non-ionizing energy deposition caused by protons, it is found that the primary knock-on atoms’ spectra of different Al _xGa _1–xN materials are similar, but the higher the content of Al, the higher the proportion of the self primary knock-on atoms generated by elastic collisions is. For the non-ionizing energy deposition produced by protons at different depths, the energy deposition due to elastic collisions is largest at the end of the trajectory, while the energy deposition due to inelastic collisions is uniformly distributed in the front of the trajectory but decreases at the end of the trajectory. This study provides a good insight into the applications of GaN materials and devices in space radiation environment.