Abstract: With the rapid development of flexible DC transmission technology, large-capacity metallized film capacitor, as one of the important supporting devices, undergoes rapid changes in port currents during wide-frequency transient processes such as continuous charging and discharging. This leads to uneven current distribution inside the capacitor, which affects the multi-physics field distribution and stable operation. We analyzed the frequency range of metallized film capacitors for flexible DC transmission applications, and introduced the major research advances in capacitor wideband calculation models, internal multi-physical field distributions (electric field, temperature, and stress), and the effects of current surges on capacitor performance. It is found that the development of well-performing capacitors requires not only the improvement of material properties but also attention to capacitor analysis and design techniques. Finally, an outlook on key technologies to enhance the performance of capacitors was presented from both design and application perspectives.