In this paper, we have proposed a new IRS system. This system used a new feature extraction method NBP. The NBP method extracts the relative connection between neighbors of pixels. Each neighbor of each pixel is thresholded by the next neighbor and encoded.After that, the NBP image is decomposed into several blocks. The mean of each block is calculated. Then, the variations of the meanare encoded. The resulted binary matrix is used as a feature descriptor of the iris. In the experimentation, the CASIA iris database is used. Good performance has been obtained for the proposed IRS. We can summarize that the proposed NBP method is interesting since it gets the relative relevant information between the neighbors of pixels.In future works, we will study the combination of the NBP method with other approaches like Gabor transform.