The majority of medium voltage distribution network is working on non-effectively grounded mode, and most of its fault type is single-phase ground fault. This thesis firstly analyzed the Single-phase ground fault process in detail, theoretically analyzed the feasibility of fault location based on signal frequency. To improve the reliability and sensitivity of this method, we use prony algorithm to extract the fault transient zero-sequence current signal and integrated, and proposed the fault location method based on frequency intergration. Finally we take simulations by PSCAD/EMTDC and MATLAB, verified accuracy and validity of procedures proposed above.