Abstract: The ladle trunnion of a steel plant was early fractured at the use of 34 times. The causes of trunnion fracture were analyzed by means of flaw detection, macroscopic observation, chemical composition analysis, mechanical property test, metallographic examination, scanning electron microscope and energy spectrum analysis. The results show that the main reason for the early brittle fracture of the ladle trunnion was the presence of cracks in the center of the trunnion. The secondary reason for the early fracture of the ladle trunnion was rough machining marks of the inner wall in center hole of the trunnion. During the service of the trunnion, the cracks expanded and eventually fractured under stress.