In this paper,phase correlation algorithm based on FFT is applied to the bar code identification.It is a widely used method of image registration.It can increase speed of items recognition and robustness of the algorithm.There is the rotation-invariant phase correlation algorithm which combines polar coordinate transform with phase correlation.They can recognize the bar code which is partly destroyed or inversed in the process of moving.The paper provides the analysis and simulation for the algorithm using Matlab,it is proven that the algorithm has the advantages of good real-time and high performance.It improves the matching precision and reduces the calculation by optimizing the rotation-invariant phase correlation.