In recent years, the Company has numerous maintenance mishaps which cause personnel injury and equipment damage, and now the Company are actively adjusting organization and training mechanics for the new equipment maintenance. In the case of an increasing workload, if the supervisor cannot use the risk management technique to predict the threats and errors in the work and avoid the damage, so that the wrong procedure repeated, and eventually will be irreversible heavy casualties. The purpose of this thesis was to combine the concept of risk management and reviewed the possible omissions in Company's current pre-maintenance risk management process and troubleshooting methods. The idea of "Prevention is better than cure" is important, but there is little discussion about the possible threats and errors risk factors in the maintenance procedure. This thesis was conducted a case study of the Company's mechanic mishaps history to develop the potential risk might occur in the maintenance, to provide maintenance personnel pre-discussion and strategy for crisis occurred. Within limited resources, through the maintenance personnel to identify a variety of possible risks in the maintenance procedures, and use continuous identification, control, and reduction achieve "zero risk" target.