Abstract: Complex and precise aluminum alloy parts can be manufactured by selective laser melting（SLM）. The principle of SLM forming technology was introduced and the research progress of SLM forming aluminum alloy defects in the world was described. The forming reasons and control methods of five different defects including balling, porosity,residual stress and cracking, oxidation inclusion and alloying element loss were analyzed, and the future development tendency was forecasted briefly.