Abstract: The 3-D finite element model for 7000 series aluminium alloy lug attachment with through cracks was established to study the effects of the lug′s structure parameters such as ratio of outer radius to inside radius, bevel angle and crack length under two types of damage model of single-edge crack and double-edge crack, on I-type stress intensity factor KI by simulation. The results show that in the same equivalent crack dimensionless length the effects of crack growth and bevel angle on KI in the two types of damage model were basically accordant. Lugs with R2/R1>2 benefited the damage tolerance design and examination. For the lug with 15°-25° bevel angles, the value KI was obviously less than the straight lug′s at the same crack length.