Considering the difficulty of accurately and fast location of ROI of inner-knuckle-print, a new location algorithm is presented forward based on dimension reduction. This algorithm transforms 2-dimension image data to two 1-dimension data by projecting the binary image in vertical and horizontal direction, and then aligns ROI images through the comparison of the two 1-dimension data.This leads to rapid and efficient recognition. The experimental results verify that it is rapid and effective than traditional methods.