Abstract: Fatigue crack propagation laws of aluminum alloys under Ⅰ-Ⅲ combined loading were investigated by finite element simulation and fatigue crack growth experiment,and the stress intensity factors under various loading conditions,the energy field around the crack front and the radius of the plastic zone were obtained.The effects of mode Ⅲ loading on the energy field around the crack front and the stress intensity factor under mode Ⅰ loading were analyzed on the basis of studies on mode Ⅰ loading.Numerical results show that under the condition of Ⅰ-Ⅲ combined loading,the stress intensity factor decreases with the increasing of mode Ⅲ loading,but the radius of the plastic zone near the crack increases.Mode Ⅲ static loading can slow down fatigue crack propagation,and to some extent,the fatigue crack growth rate under combined Ⅰ-Ⅲ loading decreases with the increasing of mode Ⅲ static loading.Mode Ⅲ cyclic loading can speed up fatigue crack propagation,and to some extent,the fatigue crack growth rate under Ⅰ-Ⅲ combined loading increases with the increasing of mode Ⅲ loading.