The complex characteristics of the fault signal in the case of fault of the distribution network bring severe challenges to the study of fault recording of power system. In this paper

the searching step is taken as an adaptive variable

and a kind of fault signal recording method based on the improved adaptive Prony algorithm is proposed. This method takes the mean square relative fitting error as the criterion

and the sub-segment boundary points are searched by the variable step size. At the initial stage of the search

a large step length is used to establish the approximate boundary point

and then the step size is gradually reduced to determine the accurate boundary point of the sub-segment. The simulation results show that the improved adaptive Prony algorithm can significantly improve the computational efficiency while ensuring the correctness and effectiveness of the actual fault signal analysis and processing.