Detection of High Impedance Fault (HIF) that is mainly occurred in MV power systems has been a challenge due to its low current magnitude. A new HIF detection approach based on correlation functions is applied on the voltage and current signals in this paper. Twelve indices based on correlation functions are implemented and tried on a lot of cases. Some of them which have clearly different values for no-fault and HIF conditions are chosen. Simulation results prove the efficiency of proposed method for HIF detection.