The imaging detectors based on the electron multiplication charge splitting anode of micro-channel plate are often used for weak signal detection such as planetary atmosphere and airglow. In view of the problem of detector imaging distortion caused by unequal gain of detector readout circuit, the theoretical analysis combined with MATLAB simulations were used to reveal the formation mechanism of different distorted images, and a gain compensation method of detector readout circuit was proposed to reduce the detector imaging distortion. The MATLAB simulation and experimental results show that the proposed method can effectively reduce the detector imaging distortion due to the unequal gain of readout circuit.