The present disclosure provides a charging method, a charging adapter and a charging system. The charging adapter includes a second controller and an adjusting circuit including a current detection circuit. The second controller is configured to receive a voltage value of a cell, search a threshold range table to obtain a current adjusting instruction. The current detection circuit is configured to detect a current value of a power signal outputted by the adjusting circuit. The second controller is further configured to calculate a difference between the current value detected and a current value specified by the current adjusting instruction, and send a calibration instruction to the adjusting circuit when an absolute value of the difference calculated is greater than a difference threshold. The adjusting circuit is configured to calibrate the power signal according to a current difference specified by the calibration instruction, and output a calibrated power signal.