In order to study the failure behavior of 7075 aluminum alloy under the combined loading of laser and external load, the joint loading experiments of 7075 aluminum alloy under different preloads and different laser power densities were carried out by using a tensile servo test machine with the maximum tension of 50 kN and a 6 kW continuous fiber laser system with the operating wavelength of 1070 nm. The tensile stress-time curve, temperature-time curve, fracture time-power density curve, and fracture temperature-power density curve were obtained. The effects of power density and preload on fracture process, fracture temperature, and fracture morphology were respectively analyzed. The results show that, under the same preload, the increase of laser power density leads to the nonlinear decline of fracture time, and the fracture temperature varies greatly depending on the size of preload. When the preload is large (330 MPa and 440 MPa), the fracture temperature increases slightly with the increase of power density, and when the preload is small (110 MPa and 220 MPa), the fracture temperature increases slightly with the increase of power density. Fracture temperature change rule is not monotonous, under the same laser power density, the fracture time decreases with the increase of preload, and the fracture behavior becomes similar with the increase of power density and the decrease of preload. At a certain power density (315 W/cm2 and 351 W/cm2), the fracture temperature increases first and then decreases with the increase of preload. The results further reveal the fracture mechanism of 7075 aluminum alloy.