Abstract: With the expansion of power grid and the integration of renewable energy, the problem of short-circuit current (SCC) has become more and more severe. As compared with other SCC limiting methods, transmission switching (TS) has better flexibility and economics. Considering that switching off too many lines would jeopardize system security, the paper proposed a SCC limiting approach based on commitment of units and TS. According to the physical meaning of self-impedance and relationship between admittance matrix and impedance matrix, the paper presented an explicit expression of SCC considering the impact of TS and CU. The expression did not induce any errors by avoiding the approximation of nonlinear terms in matrix inversion. A mixed integer linear programming (MILP) based power system day-ahead optimal scheduling model considering explicit short-circuit current constrains was proposed, while minimizing the cost of generators and TS. Finally, case studies on the IEEE 30-bus and 118-bus systems validated the effectiveness and scalability of the proposed model. Compared with the SCC calculated from the admittance matrix inversion method, the accuracy of the proposed SCC explicit expression can be validated. Moreover, a day-ahead power system scheduling with commitment of units and switching of transmission lines was obtained.