The commissioning of DC power transmission projects is divided into FAT test, equipment commissioning, subsystem commissioning, station auxiliary system commissioning, and system commissioning. The purpose of combination test is to comprehensively inspect the functionality, performance, and interface functions of equipment in the secondary system from the point of whole power system. The purpose of equipment commissioning is to confirm the equipment integrity during transportation, to check the status and installation quality of the equipment, to test whether the equipment can safely be charged, loaded and start, and whether the performance of the equipment can meet the requirements of the contract and technical specifications. Subsystem commissioning is the energizing or startup test of all independent subsystems in the converter station, the purpose of which is to prove that several components or devices can be combined into a subsystem to operate safely, and to check whether their functions and performance can meet the requirements of the contract and technical specifications. The purpose of station auxiliary system commissioning is to check the function of a single converter station according to the requirements of the contract and technical specifications, and also to prepare for end-to-end system commissioning. The purpose of system commissioning is to comprehensively assess the performance of all equipments and the secondary control and protection system of the UHV DC project, to test whether the performance indicators of the DC power transmission system can meet those stipulated in the contract and technical specifications, and to ensure the security and reliability of the equipments and system after the project is put into operation. With system commissioning, the system performance of the DC power transmission project can be comprehensively and correctly understood and assessed.