A communication apparatus, an electronic apparatus and an antenna adjustment method thereof are provided. The communication apparatus includes an antenna system, a tuning portion and a switch circuit. The antenna system includes at least two antenna units. The tuning portion is disposed between the at least two antenna units and includes at least two branch units. The switch circuit is coupled to the tuning portion. The switch circuit switches a conduction from a first one of the branch units to a second one of the branch units according to a switching signal. The switching signal is related to performances of the antenna system. Accordingly, a dynamic and flexible adjustment mechanism can be provided to increase throughput and improve users' internet experience.