Abstract: A scheme of network time protocol (NTP) was improved based on K-Means algorithm, and was applied to synchronize main station with concentrator in the power information collection system. According to the NTP timing model, the clock deviation threshold was deduced. The distortion data of clock deviation values were filtered based on the clock deviation threshold, and better sample data were kept. An improved K-Means algorithm was used to cluster and iterate on the retained sample data, and the actual clock deviation value was obtained. The actual clock deviation value was compensated to the concentrator time, and the clock synchronization between main station and concentrator was completed. The accuracy and practicality of the proposed scheme are verified by experiments on the time data of the main station and the concentrator provided by a power supply company.