1. A method for acquiring descriptive information of a plurality of images, comprising: performing a feature point detection with respect to each image of the plurality of images, so as to obtain a plurality of feature points of each image; acquiring 0-level descriptive information of the plurality of images, wherein the 0-level descriptive information of each image of the plurality of images is generated in accordance with a plurality of first local feature descriptors for the image and a plurality of first visual words, wherein the plurality of first local feature descriptors are obtained on the basis of the plurality of feature points of the image and the plurality of first visual words are obtained on the basis of the plurality of first local feature descriptors for the plurality of images; and acquiring (n−1)-level descriptive information of the plurality of images, wherein the following are performed for each image: performing a division of the image for the (n−1)th time, so as to obtain a plurality of (n−1)-level sub-images of the image; obtaining a plurality of nth local feature descriptors for the image by obtaining nth local feature descriptors for the image at the (n−1)-level sub-images in accordance with corresponding (n−1)-level sub-images where the respective feature points lie; clustering local feature descriptors for all the image at the (n−1)-level sub-images, to generate a plurality of nth visual words for the (n−1)-level sub-images; and generating (n−1)-level descriptive information of the image in accordance with the plurality of nth local feature descriptors and the plurality of nth visual words; wherein the nth visual words are different from the (n−1)th visual words, where n=2,3,. .. , K+1, and K is a positive integer.