The present invention relates to a system and method for an abnormal waveform in a power distribution system that quickly transmits abnormal waveform-related data of a large size by changing a protocol according to data size. The system for detecting an abnormal power quality waveform comprises: a plurality of RTUs for measuring abnormal waveform when a waveform measuring signal received, and transmitting an abnormal waveform using a protocol set according to the size of the abnormal waveform; an FEP for transmitting the waveform measuring signal to an RTU installed in a failure section, and receiving and storing the abnormal waveform from the RTU; a main server for transmitting the waveform measuring signal through the FEP to the RTU installed in the failure section, performing controlling to measure the abnormal waveform generated in the failure section, and receiving and displaying the abnormal waveform according to the waveform measuring signal.