The invention discloses a fast charging system for a battery based on PWM feedback control, which comprises a single chip microcomputer controller, a relay alarm unit, a switching power supply, a PWMdriving unit, a thyristor on-off control unit, a battery, a voltage and current acquisition unit, an ADC conversion unit and a communication unit. The system realizes fast charging of the battery by means of feedback control of PWM waves. The system changes the duty cycle of the PWM waves continuously by real-time monitoring on the battery charging process for variable voltage intermittent charging, that is, voltage is kept unchanged at the beginning of the charging, constant voltage with one grade reduced is used for charging after charging for a period of time, the best charging effects whenthe charging current is gradually reduced are achieved, the system has a simple structure, state monitoring on the battery can be carried out in real time, the safety and the reliability are high, and the service life is ensured to a certain degree.