The invention discloses a method for estimating and restraining a distributed IQ (In-Phase Quadrature branch) imbalance. The method comprises the following steps: demodulating a received OFDM (Orthogonal Frequency Division Multiplexing) system signal; outputting a training signal S(k) and a data signal Y(k) in a frequency domain; for the training signal S(k), removing the modulation information in the training signal S(k) to obtain an interference term J(k) caused by the IQ imbalance; estimating IQ imbalance parameters A(k) and B(k) caused by a sending end and a receiving end of each subcarrier in the frame where the training signal S(k) is located; updating the IQ imbalance parameters A'(k) and B'(k) according to the imbalance parameters A(k) and B(k); carrying out channel equalization on a frequency domain signal Y(k) to obtain signals X and X'(k); correcting the IQ imbalance for the signal X'(k). According to the method, the application range is wide, the IQ imbalance related to or irrelated to a frequency point in a radio frequency circuit at the sending end or the receiving end can be estimated and restrained, moreover, the influence of a frequency offset can be prevented effectively and the operation complexity is low.