The invention discloses a digital system for image rejection of a low-intermediate-frequency receiver and an implementation method thereof. The digital system comprises a direct-current calculation module, a first subtractor, a conjugated calculation module, a power calculation module, a self-adaptive filter calculation module and a plurality of band-pass filter modules; the direct-current calculation module is used for receiving I and Q data and outputting I0 and Q0 data; the first subtractor is used for receiving the I and Q data and the I0 and Q0 data so as to obtain I1 and Q1 data; the conjugated calculation module is used for receiving the I1 and Q1 data so as to obtain I2 and Q2 data; the power calculation module is used for receiving the I1 and Q1 data so as to obtain IQ-POW data; the self-adaptive filter calculation module is used for receiving the I1, Q1, I2, Q2 and IQ-POW data so as to obtain I4 and Q4 data; and the plurality of band-pass filter modules are used for receiving the I4 and Q4 data so as to obtain I5 and Q5 data. IQ mismatch can be improved obviously and stably although the digital system disclosed by the invention has a relatively simple structure.