The present disclosure provides a 5th generation (5G) broadband dual-polarized base station antenna of a multimode resonance structure, including: a first resonance structure, a main radiating unit, a feed balun set, and a metal reflecting plate, where the feed balun set is disposed on the metal reflecting plate, the main radiating unit is disposed on a first feed balun and a second feed balun, and the first resonance structure is disposed on the main radiating unit; the main radiating unit includes a second resonance structure and a third resonance structure, the first resonance structure is configured to control a resonance point at a high frequency, and the third resonance structure is configured to control a resonance point at a low frequency; and the feed balun set is configured to provide a balance current for the main radiating unit and the first resonance structure.