Breaking parts of transmission lines can increase the electric distance among over standard substations and it is an effective measure of limiting short-circuit current of 500 kV power grid. As regards the choices of breaking transmission lines， the restrictive effect of short-circuit current should be considered as well as the integrality of 500 kV power grid. Moreover， it is extremely difficult to seek a combination of breaking transmission lines from thousands of combinations， which can limit short-circuit current to the maximum by breaking the least transmission lines. By analyzing the influences of breaking transmission lines on elements of the impedance matrix， the relationship between breaking several transmission lines and the sensitivity of self-impedance of over standard substation is derived. Based on the sensitivity， an optimization algorithm for short-circuit current limitation of 500 kV power grid by adjusting power grid configuration is proposed. Through calculating the maximum value of weighted sum of the sensitivity， the optimal combination of breaking transmission lines can be rapidly sought by the optimization algorithm. Accordingly， it will avoid the tedious process of checking all the combinations of breaking transmission lines one by one. The effectiveness of the proposed algorithm is verified by the adjustment scheme of 500 kV power grid in Guangdong Province.