The invention discloses a method for determining the installation position of a direct-current power grid power-flow controller. The method comprises the steps of obtaining an incidence matrix between circuit current and injection current in a direct current network and an admittance matrix of a direct-current power grid; according to the incidence matrix and the admittance matrix, obtaining the calculation relational expression among the circuit current, the injection current and the direct voltage of the power-flow controller through calculation; according to the calculation relational expression, obtaining a relative circuit current-limiting margin vector and a comprehensive circuit current fluctuation ratio vector; according to the obtained relative circuit current-limiting margin vector and the comprehensive circuit current fluctuation ratio vector, obtaining a judgment vector through calculation according to a predetermined formula; selecting a predetermined number of elements with the numerical element values from large to small inside the judgment vector, wherein the circuits corresponding to the predetermined number of elements are the installation position of the power-flow controller. According to the method, the installation position of the direct-current power grid power-flow controller can be determined.