Considering the mutual inductance between lines, most of the fault analysis methods construct different compound sequential networks for different fault types, which causes large workload and makes it difficult to debug. Therefore, this paper proposes a short circuit current calculation method for two transmission lines considering mutual inductance between lines. In this paper, the node impedance matrix of the both fault lines’ ends and the impedance of fault lines are used as inputs. The parameters of the original node impedance matrix are modified or expanded by adding tree branches or link branches to deal with mutual inductance between lines or adding fault points. Then, the sequence network equations at the fault point of the two transmission lines can be constructed. This paper presents a universal method for constructing the fault boundary condition matrix for two transmission lines. The phase-sequence transformation is used to construct the fault boundary condition equations for each sequence network. The voltage and the current at each fault point can be solved in conjunction with the sequence network equations. Finally, a fault simulation model of power network is built by PSCAD/EMTDC, and the results verify the correctness of the method.