With the more and more serious hamonic pollution, it has become an important task to analyze and restraint harmonic on offshore platform power system’s design and run. Simulation sortware has gradully been the main method used by electrical engineer to analyze and study harmonic in power system. The paper outlines the characteristic and main restraint method of power system harmonic analysis, then introduces the characteristic of ETAP Powerstaion which is a formidable power system analysis simulation software,how to use ETAP Powerstaion to carry on harmonics analysis to power system and forcast the filter’s types are put forward at last.