By analyzing the response characteristics of large-format infrared detectors, we found that the response nonlinearity in different areas is caused by the characteristics of the camera itself. After the traditional two-point correction method or nonlinear curve fitting method corrects the large-format array detector, the correction residuals and visual effects are relatively poor. In this study, on the basis of eliminating blind elements, according to the nonlinear response characteristics of the detector, the entire array is divided into eight regions for nonlinear fitting correction, the bias coefficient of each region was corrected, and the non-uniformity correction algorithm of the BP neural network was used to deal with the non-uniformity problem caused by region division. After correction, the residual non-uniformity of each black body temperature point image was on the order of one-thousandth, the spatial noise was already very close to or smaller than the temporal noise, and the local residual non-uniformity reached below 0.002, which was significantly smaller than the temporal noise.