The invention relates to a parallel connection three-terminal direct current power transmission system and a power coordination control method of the same. The parallel connection three-terminal direct current power transmission system includes LCC (Line Commutated Converter) rectifier stations and LCC inverter stations, wherein two LCC converters are connected through a direct current power transmission line; the direct current power transmission line is connected with a VSC (Voltage Source Converter); each LCC rectifier station is controlled by a constant power; each LCC inverter station is controlled by the constant direct voltage/constant extinction angle; and the VSC is controlled by the constant power. The power coordination control method includes the steps: respectively acquiring the direct current command values of the two rectifier stations; when the VSC is operated in a rectification mode, the current command value of the LCC inverter station is obtained when the sum of the direct current command values of the two rectifier stations subtracts a set current margin value; and when the VSC is operated in an inversion mode, the current command value of the inverter station is obtained when the difference between the direct current command values of the two rectifier stations subtracts the current margin value. The coordination control strategy is simple and easy to use, and can avoid complicated coordination and cooperation between each terminal of a pure LCC type multi-terminal direction current, and has a great practical engineering value.