The concept of distributed power generation and distributed energy access systems is introduced, and also a precision power harmonic analysis algorithm based on Blackman-harris window and triple-spectrum-line interpolation FFT, and then a harmonic power meter is designed ,hardware structure and algorithm flowchart are given . Applications of harmonic power meter in monitoring system of distributed power generation and two kinds of accessing system of 0.4kV level and 10kV level distributional power source are given. It is significant for application of harmonic power meter and accurate measurement of harmonic in distributed energy access system.