Abstract: The fracture accident of fiberglass sucker rod occurred in the process of oil production. The fracture causes of the fiberglass sucker rod were analyzed by means of size measurement, glass transition temperature detection, resin content detection, mechanical property test and hardness test. The results show that the tensile strength of the fiberglass sucker rod was lower than the required value, and it bore repeatedly tension and compression during operation. The fiberglass gradually fractured into a split and scatter shape. The eccentric wear between coupling and shaft wall accelerated the fracture of rod.