The invention relates to a fault branch identification method and a system based on T node current, wherein the fault branch identification method comprises steps of: acquiring the current analog quantities as shown in the description on the M side, the current analog quantities as shown in the description on the N side and the current analog quantities as shown in the description on the S side ofthe T-connection line; acquiring the current analog quantities as shown in the description and the current analog quantities as shown in the description of the T nodes on the M, N and S sides; judging whether the T-connection line is a three-terminal mode or a two-terminal mode; performing fault phase selection and judging whether there is a fault phase selection result; and if there is a fault phase selection result, locating fault branch in three-terminal mode or in two-terminal mode according to which is shown in the description, which is shown in the description and Kirchhoff's current law. According to the fault branch identification method and the system based on T node current, when the T-connection line fails, the current on the three sides of the T-connection line and the currenton the three sides of the T-node judged the fault branch according to the Kirchhoff's current law. If the system is normal, the fault branch judging is not performed. The fault branch can be accurately identified, and system misjudgment is avoided.