Harmonics can be very harmful to power electronic equipment. With the widespread use of modern electronic equipment, the generation of harmonics has become more common. These harmonics not only come from non-linear loads but can also be caused by faults or instability in the power system. Therefore, suppressing harmonics is crucial to maintaining the stability and normal operation of the power system. In recent years, experts have studied the harmonic problem, there are a large number of harmonic suppression methods, and the basic idea is divided into two, one is to transform the power electronic equipment itself; the other is to install harmonic compensation devices. In this report, three feasible harmonic suppression methods are selected for these two main ideas, harmonic suppression based on feed-forward compensation, harmonic suppression based on transformer, and harmonic suppression based on filter. For the public to have a clear enough understanding of these methods, the backgrounds of these three methods are introduced, the basic working principles are analyzed, and the effects of harmonic suppression are analyzed and summarized, which will help subsequent researchers sort out research ideas. Finally, according to the current shortcomings of the three methods, including a small range of applications, limitations of harmonic detection technology, and so on, the future development of harmonic suppression methods is prospected.