In order to effectively restrain the harm caused by harmonics injected by an ultrahighvoltage direct current (UHVDC) converter station to an alternating current (AC) system, according to the basic principles of the design of AC filters, a set of AC filter design software for UHVDC projects was developed. The software has various functions, including inputting, modification, saving, and batch generation of relevant parameter files; configuration of AC filters; analysis of harmonics; calculation of filter performance and steadystate rating; importing of result data into the database; and generation of word report forms. The software was used to design AC filters for a UHVDC project. The results show that the proposed software is flexible, accurate, convenient, and universal.