In order to study the problem of the guidance accuracy reduction caused by the inconsistency of the four acquisition channels in the information processing circuit of the semi-active laser guidance seeker, the reason of the difference of the response between the sampling channels was analyzed and studied. The gain control circuit in the information processing circuit was studied. The key points of the design were analyzed, and the design principle of a gain control circuit was given. An inter-channel response inconsistency correction method based on the gain control circuit was used to correct the inconsistency of discrete gain points used in the actual flight of a missile (or a bomb). The effectiveness of the correction method was verified by comparing the linear curve before and after correction with the simulation data of hardware-in-the-loop. The experimental results show that the linear circular error probable (CEP) of the seeker is more accurate and the CEP of the semi-physical simulation can be reduced by about 50%. This study provides an effective method for improving the precision of semi-active laser guidance.