Abstract: A variety of testing equipment were used to study the broken triangular bracket. The results show that the structure, composition and hardness of triangular scaffold are qualified. The crack source is located on the fracture surface,where the chemical composition is normal and there are no other inclusions. The inside of the fixture used in the bench test has serious wear and tear, and the surface is uneven. Under the repeated alternating stress, the fracture location of the triangular bracket is damaged and the crack source is produced, which eventually leads to the early fracture, which is the fundamental reason for the fracture. The fatigue life is 256000 times, which can meet the technical requirements.