The present disclosure provides a charging system, a terminal, a power adapter and a charging line. The terminal includes a first controller and M charging input interfaces. The power adapter includes a second controller and N charging output interfaces. When at least one of the N charging output interface is coupled to the charging input interfaces of the terminal, the second controller and the first controller communicate with each other to determine the number of charging output interfaces of the power adapter coupled to the terminal, and a charging current outputted from the power adapter to the terminal is adjusted according to the number of charging output interfaces of the power adapter coupled to the terminal.