Digital automatic gain control method and system thereof

The invention provides a digital automatic gain control method and a system thereof. The method comprises the following steps that: a bit cutting output signal is feedbacked to carry out power statistics, so that an average power value is obtained; the average power value is compared with a preset strength grade parameter to obtain a corresponded step value and a corresponded gain adjusting direction value; according to the step value, the gain adjusting direction value and a preset initial gain value, a gain value is adjusted; the adjusted gain value is multiplied by an input signal to carry out gain compensation; and then a bit cutting output is carried out on a signal after the gain compensation. According to the digital automatic gain control method and the system thereof provided in the invention, an output signal after the bit cutting is feedbacked to carry out power statistics, so that a power state of a current output signal can be better reflected and strength fluctuation of the output signal is controlled in a certain range.