Along with the development of network, especially the connecting of UHV substations, the short-circuit current in 500 kV network increases prominently in Beijing-Tianjin and Northern Hebei Area. In this paper, short-circuit current problems of 500 kV network caused by connection of UHV substation in Beijing-Tianjin and Northern Hebei Area are studied. The self-impedance models are used to analyze the short-circuit current’s constructions and mechanism in 1000 kV and 500 kV substations. On the basis of analyzing the main affecting factors for short-circuit current, the suitable limiting measures are proposed. Finally the conclusions are proved by the calculation and analysis in actual power system.