Abstract: The influences of casting cooling speed on the solidification behavior of A380 and A383 aluminum alloys during high pressure die casting were studied. Three cylindrical molds and three-step filling die-casting dies were designed and the high-pressure die-casting experiments were carried out. The microstructure of cylindrical castings and three-step filling high-pressure castings was compared,and the effects of cooling rate on the solidification characteristics such as dendrite arm spacing and mechanical properties of die-cast aluminum alloy were analyzed. The results show that there is a strong positive correlation between the dendrite arm spacing and the cooling rate during the high-pressure die casting process,and the mechanical properties and cooling rate of the alloy are also positively correlated with the dendrite arm spacing of the alloy. However,with the gradual increase of the cooling rate,the increase amplitude of mechanical properties of the alloy decreases gradually.