Abstract: The rapid solidification process of liquid Ti_100-xAl_x（x=10,25,50,75,90） alloys was simulated by using molecular dynamics.And the evolution characteristics of melt microstructure during solidification were analyzed by the double body distribution function and HA （Honeycutt-Anderson） bond type index method.The curves of the average atomic volume with temperature show that at the cooling rate of 5×10¹²K/s,all rapidly solidified alloys are amorphous.The double-body distribution function of the alloy during cooling shows the typical characteristics of amorphous.The alloy composition has significant influence on microstructure and amorphous forming ability.The Ti₂₅Al₇₅ alloy has the strongest amorphous forming ability and contains the most bond pairs that characterize the icosahedral structure.