Through drilling on carbon fiber reinforced polymer(CFRP)/titanium alloy(Ti6Al4V) stacks with the carbide twist drill, this paper studied tool wear mechanisms, the influence of titanium layer processing parameters for tool wear and effects of cutting tool wear on the largest tear length of hole entrance.The results showed that the main area of wear is the horizontal and the flank,and the wear of the rake face is not obvious. When drilling the titanium alloy layer,low speed and low feed rate can be used to reduced tool wear.With the increase of the number of holes,the hole entrance of the titanium alloy layer is more stable.