Effects of target thickness and macroscopic interface on the ballistic performance of Ti6Al4V titanium alloy were investigated. The monolithic Ti6Al4Vtitanium alloy with thickness varied between 10mm and 30mm and the armor configurations of the double-layered (15+15)mm Ti6Al4V titanium alloy were normally impacted by the 12.7mm AP. The results showed that the ballistic performance increased with the increase of the target thickness. Significant improvement was observed when the target thickness varied between 15mm and 20mm, this was considered to be related to the failure mechanism involved. The 30mm monolithic Ti6Al4V titanium alloy was more effective than the (15+15)mm double-layered Ti6Al4V titanium alloy, this was thought to be related to no exist shear strength on the macroscopic interface between the double-layered targets.