Abstract: This paper proposes a current differential protection method based on harmonic information to address the problems of complex fault currents caused by the integration of distributed power sources in active distribution networks and the susceptibility of traditional protections to misoperation or refusal. By using the Prony algorithm to extract the harmonic components of the fault current, a differential protection criterion is constructed to achieve rapid and accurate identification and isolation of the fault area. The simulation results show that this method can effectively distinguish faults within and outside the zone in various fault scenarios, improve the reliability and speed of protection actions, and is suitable for distribution network protection with high proportion of distributed power access.