Maximally Stable Extremal Regions are robust to complex affine distortion and illumination changes between reference image and real-time image. On the basis of deeply research on the SIFT descriptor, this paper propose a description algorithm for MSER using SIFT descriptor. The Second central moment is used in the algorithm to make ellipse adjustment for each irregular MSER. Then a self-adaptable rectangle area, whose side is proportional to the minor axis of the ellipse, is constructed encircling each ellipse centre. Finally, a SIFT feature vector is formed to express the MSER, after processing the statistic characteristic of all pixels’ gray gradient in the rectangle aero. A reasonable range of a self-adaptable rectangle area side is presented in the paper. Matching experiment results show that our algorithm is highly distinctive and stable.