Nonuniformity exists in all IRFPA. Lots of nonuniformity correction methods have been developed to solve the problem. One of the most valuable methods is two-point correction algorithm. Based on the analysis of two-point correction algorithm, an improved multi-point algorithm is put forward and its implementation is also discussed. This algorithm has large dynamic range to effectively overcome nonuniformity brought by nonlinear characteristic of IRFPA detector units. And it has the advantages of high precision, fast processing speed, and easy to realize in real time. Its effectiveness is demonstrated in engineering. The experimental results are given in the end.