The invention discloses a method for determining the optimal segmentation scale of satellite image segmentation based on information gain rate, includes obtaining high-resolution satellite remote sensing image, preprocessing, selecting representative region as sample region determined by optimal segmentation scale, classifying surface features of sample region, obtaining image classification result of sample region as reference image determined by optimal segmentation scale, and obtaining image classification result of sample region as reference image determined by optimal segmentation scale;setting a series of segmentation scale parameters from small to large, using multi-scale segmentation technology, the sample image is segmented in multi-scale to obtain a series of segmented object vectors; Based on Shannon information entropy formula, the information entropy of reference image and segmentation vector is calculated, and the conditional entropy of reference image with segmentationvector is calculated, then the information gain and information gain ratio of segmentation vector are calculated. The optimal segmentation scale is selected according to the principle of maximum information gain rate. Finally, based on the optimal segmentation scale, the original image is segmented at multiple scales.