Low cycle fatigue behavior of Al-7Si-0.3Mg alloy was examined by mechanical fatigue testing with equivalent strain amplitude varied from 0.15% to 0.35%

and the dislocation evolution in the specimens was observed by TEM（transmission electron microscope）. The results indicate that the dislocation structure is closely dependent on strain amplitude

and the density of dislocation in failure specimens is increased with increasing in equivalent strain amplitude. Cyclic hardening can be found as a result of the dislocation interaction and particle pinning

and hardening region can been throughout the entire fatigue process with the strain amplitude more than 0.35%. Fatigue life is decreased with the increase of the equivalent strain amplitude

confirming to the equation of the Manson-Coffin.