Abstract: A end frame joint of 7050 aluminium alloy broke during hoisting and transferring. By means of simulation analysis, macro analysis, micro analysis, metallographic examination, hardness test, mechanical properties test and chemical composition analysis, the fracture causes of end frame joint were analyzed. The results show that the fracture of the 7050 aluminium alloy end frame joint belongs to overload fracture, and the maximum stress of the hoisting point exceeded the strength limit of the material due to the irregular hoisting operation. Finally, the overload fracture of the end frame joint occurred at the hoisting point.