The joint action of influencing factors leads to the occurrence of safety accidents, however, the importance of influencing factors must be further studied. Considering the fatal accident caused by the failure and downfall of the construction lift in Hengshui, Hebei as an example, the following conclusion was drawn according to the investigation report: bolts in the standard section of the construction elevator were not installed. Acceptance and commissioning did not satisfy the requirements and standards of industries and were the direct cause of the accident (dominant factor). The indirect causes (recessive factors) included the indifference in relevant units of the work safety, disordered management, non-standard systems, and incomplete systems.