The edge terminals of smart grid always generate a large amount of time series data，which is of great significance to the intelligent operation of smart grid. In order to protect the privacy of data and reduce the requirement of transmission bandwidth and delay，the data often needs to be stored locally. Due to the regularity of electrical equipment，the generated time series data has great redundancy，which provides a solution to the challenge of data storage at edge equipment. In this paper，an edge electricity data deduplication method is proposed based on dynamic time warping，which calculates the similarity between data to eliminate data redundancy and achieve the purpose of data deduplication. Finally，based on the real-world time series data of smart grid，the effectiveness of the proposed data deduplication method in edge computing security protection system is analyzed and verified.