A method for calculating image similarity, comprising the steps of: S1: extracting feature points and corresponding feature vectors from a first image and a second image, respectively; S2: pairing all the feature points in the first image with all the feature points in the second image according to similarity by comparing first distances between the feature vectors in the first image and the feature vectors in the second image; S3: sorting the paired feature points according to the similarity from high to low, and selecting top N feature point pairs in the first image and the second image; S4: respectively randomly selecting n reference points from the top N feature point pairs in the first image and the second image, and respectively calculating X-direction and Y-direction relative positions of remaining feature points relative to the n reference points in the first image, and respectively calculating X-direction and Y-direction relative positions of remaining feature points relative to the n reference points in the second image; and S5: calculating an X-axis distance according to the X-direction relative positions of the remaining feature points relative to the reference points respectively in the first image and the second image, calculating a Y-axis distance according to the Y-direction relative positions of the remaining feature points relative to the reference points respectively in the first image and the second image, and with respect to the calculated X-axis distance and the Y-axis distance, setting a threshold range to determine whether the first image and the second image are a same image, wherein the step S5 specifically comprises the steps of: S51: setting the X-direction relative positions x 11,..., x 1i,..., x 1n of one of the remaining feature points relative to the n reference points in the first image as vector A; S52: setting the X-direction relative positions x 21,..., c 2i,..., x 2n of one of the remaining feature points relative to the n reference points in the second image as vector B; S53: calculating the X-axis distance between vector A and vector B; S54: calculating in a same manner the Y-axis distance between vectors of the Y-direction relative positions of one of the remaining feature points in the first image and the second image with respect to the n reference points. S1: extracting feature points and corresponding feature vectors from a first image and a second image, respectively; S2: pairing all the feature points in the first image with all the feature points in the second image according to similarity by comparing first distances between the feature vectors in the first image and the feature vectors in the second image; S3: sorting the paired feature points according to the similarity from high to low, and selecting top N feature point pairs in the first image and the second image; S4: respectively randomly selecting n reference points from the top N feature point pairs in the first image and the second image, and respectively calculating X-direction and Y-direction relative positions of remaining feature points relative to the n reference points in the first image, and respectively calculating X-direction and Y-direction relative positions of remaining feature points relative to the n reference points in the second image; and S5: calculating an X-axis distance according to the X-direction relative positions of the remaining feature points relative to the reference points respectively in the first image and the second image, calculating a Y-axis distance according to the Y-direction relative positions of the remaining feature points relative to the reference points respectively in the first image and the second image, and with respect to the calculated X-axis distance and the Y-axis distance, setting a threshold range to determine whether the first image and the second image are a same image, wherein the step S5 specifically comprises the steps of: S51: setting the X-direction relative positions x 11,..., x 1i,..., x 1n of one of the remaining feature points relative to the n reference points in the first image as vector A; S52: setting the X-direction relative positions x 21,..., c 2i,..., x 2n of one of the remaining feature points relative to the n reference points in the second image as vector B; S53: calculating the X-axis distance between vector A and vector B; S54: calculating in a same manner the Y-axis distance between vectors of the Y-direction relative positions of one of the remaining feature points in the first image and the second image with respect to the n reference points. S51: setting the X-direction relative positions x 11,..., x 1i,..., x 1n of one of the remaining feature points relative to the n reference points in the first image as vector A; S52: setting the X-direction relative positions x 21,..., c 2i,..., x 2n of one of the remaining feature points relative to the n reference points in the second image as vector B; S53: calculating the X-axis distance between vector A and vector B; S54: calculating in a same manner the Y-axis distance between vectors of the Y-direction relative positions of one of the remaining feature points in the first image and the second image with respect to the n reference points.