In order to solve the problems of high energy consumption， difficulty in particle size control and serious pollution in the preparation of nano-aluminum powder. green and safe preparation of nano-aluminum powder is fulfilled by liquid chemical method through adding diisobutyl aluminum hydride （DIBAL） to aluminum chloride-1-ethyl-3-methylimidazole chloride（AlCl₃-EMIC） ionic liquid with the molar ratio of 2∶1. By means of X-ray diffraction （XRD）， nano-particle size detection， transmission electron microscopy （TEM）， scanning electron microscopy （SEM）， energy dispersive spectrum of X-ray （EDS） and linear scanning voltammetry （LSV）， the nano-aluminum powder was characterized and its growth process and reaction mechanism were explored The results show that when DIBAL concentration is 0.25 mol·L^-1 and reaction time is 0.5 min， the non-agglomerated aluminum powder with uniform particle size of 40-100 nm is obtained， which is more uniform than the one obtained by other liquid chemical methods. The abnormal growth of aluminum powder is observed at different DIBAL concentrations， which is related to the Ostwald ripening. In addition， the AlCl₃-EMIC ionic liquid is not only the reaction medium， but also the Al source of the nano-aluminum powder.