The invention discloses an SOGI-based single-phase transformer short-circuit parameter on-line real-time identification method. The identification method comprises steps of establishing a T-type equivalent circuit of a single-phase transformer; listing the short-circuit impedance parameter equation and the T-type equivalent circuit equation of the transformer; respectively obtaining the d axis equation and the q axis equation of the T-type equivalent circuit in a dq coordinate system; and using a SOGI-FLL model to extract fundamental wave components and fundamental wave orthogonal components of all input signals, obtaining the d axis component and the q axis component of all input signals in the dq coordinate system, and calculating the short-circuit resistance values Rk and Xk of the single-phase transformer, thereby achieving on-line monitoring of operation states of single-phase transformer windings. When windings of the transformer deforms and break down, the short-circuit impedance of the transformer will change. By measuring voltage and current of the primary side and the secondary side of the transformer, short-circuit parameters of the transformer windings can be identified. Thus, on-line monitoring of the operation states of the transformer windings is achieved; potential risks of the transformer can be found as soon as possible; fault points can be timely removed; operation accidents can be avoided; and service lifetime of the transformer is extended.