Commissioning is an effective means to guarantee the quality of power engineering. Pre-commissioning is the work carried out between the completion of equipment installation and the start of commissioning to ensure the smooth progress of commissioning. In this paper, the operation flow and application effect of commissioning and pre-commissioning are analyzed. The influence of the whole commissioning process on power engineering is further explored. The conclusion shows that the commissioning of electrical equipment in power engineering can effectively guarantee the construction quality, save time and cost, and make the project delivered on time.