The invention discloses a method for analyzing OPGW (optical fiber composite overhead ground wire) system grounded short-circuit current on the basis of an extended phase-component method. A phase wire and an OPGW are taken as a whole, the interaction of the phase wire and the OPGW is considered, and the phase wire and the OPGW are analyzed with a consistent analysis model. By means of the method, the electrical quantities, distributed along wires, of short-circuit current and the like on the OPGW and the phase wire of a power transmission system can be accurately obtained when single-phase ground short circuit happens. The method is applicable to two different situations of a power transmission system of a single-ended power supply and a power transmission system of a double-ended power supply; the mode for operating two OPGWs simultaneously in the power transmission system is also contained; a complicated operation mode that whether the two OPGW wires are sectionally insulated and whether pole towers are grounded step by step is further contained; the distribution rule, calculated with a new algorithm, of the short-circuit current on the OPGWs is further contained. The method adopts a mature technology and is high in reliability.