A charge control system for lithium battery using pulse width modulation is provided, and it detects the existing voltage of the charging lithium battery by a voltage detector and passes this voltage value to a microprocessor preset in the hand-held apparatus. Thus, the microprocessor can decide the applicable charge stage and confirm the status of the charging battery depending on the different Voltage values in real time. Next, the microprocessor controls a control unit by a pulse width modulation signal to modulate the power-source, which comes from an adaptor, as a constant current or a constant voltage to charge the battery. Accordingly, the charge process is completed by repeating the voltage detection and the duty cycle modulation of the control unit.