Abstract: The Al-Ru alloy nano-powders containing 50 wt% Ru were prepared by mechanical alloying and following anneal method. The change of phase compositions,average grain size and micro-strain of the alloy powders with the milling time during the mechanical milling process was observed and the effect of anneal temperature and anneal time on the phase compositions was also analyzed. The results indicate that with the increase of milling time,the average grain size of the alloy powders decreased but the micro-strain firstly increasd and then decreased. Al atoms dissolved into the Ru crystal completely after milling for 50 h and formed Ru(Al) solid solution. The solid solution transformed into Al-Ru intermetallics and the micro-strain decreased after anneal. The alloy powders milled for 50 h mainly composed of Al2Ru and Al5Ru2 two phases after annealed at 550 ℃,while they composed of Al2Ru,Al13Ru4 and a little Al5Ru2 phases after annealed at 700 ℃. Anneal time had slight influence on the phase compositions of the alloy powders.