Abstract: The short-circuit fault characteristics of the potential transformer(PT) based on the three-phase 4PT connection method are analyzed, and the variation patterns are derived. Firstly, theoretical analysis is conducted on the secondary three-phase voltage and zero sequence voltage values under a typical 4PT wiring method. Secondly, based on the design parameters of PT, a finite element model is established to simulate and calculate the capacitance, inductance, resistance and other parameters related to the winding, and a refined equivalent circuit model is constructed based on the parameters. Once again, based on the three-phase 4PT wiring method, a detailed analysis is conducted on the phenomenon of PT short-circuit faults and the changes in electrical characteristics of each PT after the occurrence of short-circuit faults. Finally, combined with a refined circuit model, the electrical characteristic changes after PT short-circuit fault are verified through Matlab modeling and simulation, confirming the correctness of the electrical characteristic changes. The research results provide an important basis for the online monitoring method of PT short-circuit faults, which is conducive to real-time and accurate monitoring of PT's health status without exiting the operation or disassembly.