This paper takes a fixed crane jib fracture failure accident as the research object, analyzed and calculated the force of the jib under different operating conditions by measuring the relevant data at the time of the accident, discussed the possibility of overload caused by the different distribution of the crane grab in the operating area of the cabin due to operating factors, and carried out the macro and micro failure test analysis of the jib fracture. The results show that under the action of alternating load, the manufacturing defects of the jib caused fatigue cracks due to the stress concentration formed at the defects, and the cracks continued to expand during period in use. Ultimately, due to the reduction in the load-bearing area of the crane jib, it was unable to bear the weight of the lifting operation, resulting in an overload and fracture accident. In addition, improper operation by operators during the operation process, such as rapid lifting, oblique lifting (pulling), and impact, can generate instantaneous impact loads, which can also cause the lifting arm to be unable to bear the weight of the lifting operation. The joint action of the equipment itself and improper operation by the operators ultimately led to the occurrence of an overload and fracture accident of the crane jib.