The invention relates to a DC power transmission unit black-start method without local load, and a DC power transmission system. The method comprises the following steps: controlling a standby generator to supply power for a first unit in multiple local units when multiple local units are not started, thereby starting the first unit; and controlling the first unit to respectively supply power forauxiliary engines of multiple second units in multiple local units, thereby starting the auxiliary engines of multiple second units, wherein the output power of the first unit is the operation power of the auxiliary engines of multiple second units; and controlling the first unit to supply power for the DC grid when detecting that the output power of the first unit achieves the minimum starting power of the DC grid. Through the method disclosed by the invention, the auxiliary engines of multiple second units are used as the local load, and the starting of the DC power transmission unit withoutthe local load can be realized without additionally constructing the local load or flexible DC power supply system with high cost.