Operation of non-linear loads results in the emergence of harmonic distortion waves, which are actually sinusoidal-shaped output waves being non-sinusoidal. Harmonic waves are triggering problems in the electrical system causing abnormal operation. In this final project, primary data retrieval at AR-Fakhrudin B building, Universitas Muhammadiyah Yogyakarta, has been conducted. The taken data were power transformer, current, voltage, active power, reactive power, apparent power, power factor, current THD, and THD voltage. In this study, the comparison between THD current and THD voltage using IEEE Standard 519-1992 and the calculation of active filter capacity were successfully performed. This calculation is necessary since the value of THD current is greater than the standard, thus the harmonic values should be suppressed. The result of the analysis is THD current at AR Fakhrudin B is more than IEEE standard 519-1992 so it must be reduced by harmonic active filter assembling.