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Aluminum alloy friction stir welding (FSW) tends to produce hole defects, reducing the mechanical properties of Tailor Welded Blanket (TWB). However, the effect of hole defects on the crack propagation of welding joints is not clear yet,which greatly limits the application of tailor-welded blanks. Based on the partition modeling of the FSW joint with holes for 2024 aluminum alloy, the paper studied the influence law of hole size of joint on crack propagation through the tests combined with the finite element method. The results show that the mechanical properties of the joint increase with the decrease of the hole size under quasi-static service conditions, the heat affected zone is fractured, the mechanical properties of the joint are basically the same as those without the defect when the hole diameter is less than 0.1 mm; WNZ with hole defect is fractured when the diameter of the hole is larger than 0.1 mm. The fatigue properties of the joint increase with the decrease of the hole size under the condition of fatigue load, and the sensitivity to the load decreases gradually; there will be a temperature rise in the fracture and the fracture always takes place in the WNZ with hole defect.