The non-uniformity correction algorithm of infrared image using Lagrange interpolation algorithm to calculate the offset coefficient was proposed in this paper. It overcame the shortcoming of periodic calibration for the calibration algorithm and it was less complex than other algorithms based on the scene. According to the characteristics of large amount calculation, the method of constructing SOPC system based on FPGA was used to realize the algorithm, including parameter calculation, background acquisition and calibration model. Parameters were calculated and updated according to a certain strategy. Background information module was used for collecting the information of the uniform background. Correction module was used to complete the real-time non-uniformity correction. The experimental results show that this system has the advantages of less resources, shorter delay and better imaging effect.