Interlayer burr formation in drilling of stacked aerospace materials is a common problem in aircraft assembly operations. Burrs formed at the interface of the stacked sheets need to be removed, and the deburring is a nonvalue but time and costs waste operation, particularly in automatic drilling and riveting assembly. This article presents an analytical model of the interlayer gap formation to predict the interlayer burr height, and drilling experiments were developed to understand the difference between the interlayer burr height and the interlayer gap. The impact of cutting force, spindle rational speed and feed rate was taken into consideration. Specific conclusions regarding the influence of the interlayer gap on burr formation were presented.