Embodiments of this application disclose a variable capacitor-based antenna adjustment method and a related apparatus. A first signal strength of a first communications system with a highest priority that is supported by an antenna having a variable capacitor is detected, and when the first signal strength is relatively strong to meet a first release condition, a capacitance value of the variable capacitor is adjusted to a preset capacitance value, where the preset capacitance value is closer to a second capacitance value corresponding to a working frequency band of a second communications system supported by the antenna, so that a working frequency band of the antenna having the variable capacitor is closer to the working frequency band of the second communications system, and therefore, communication quality of the second communications system is improved. Although the first signal strength is attenuated, because the first signal strength is very strong before the attenuation, the attenuated first signal strength can still meet a communication quality requirement on the first communications system. Therefore, this application can give consideration to communication quality of multiple systems supported by the antenna having the variable capacitor.