Tube hydroforming has been widely used in auto industry due to its remarkable advantages compared with conventional manufacturing via stamping and welding. The forming limit stress diagram (FLSD) which is independent of strain paths is of great significance to tube hydroforming. The FLSD of 2008T4 tube blank was established to predict fracture defect in T-shaped tube hydroforming simulation. By numerical simulation method, the stress limit and strain limit were analyzed and fracture defects were predicted. Two prediction results of the fracture defects location were the same yet the limit pressure values corresponding to fracture were different. The FLSD prediction result was close to the experiment result, so the accuracy of FLSD as tube hydroforming limit criterion was proved.