The invention discloses an automatic detection method for an overstretched region of an optical remote sensing satellite orthoimage. The method comprises the steps of firstly loading an original satellite image, an RPC parameter and a digital elevation model DEM, and iteratively calculating the size and range of the orthoimage after orthorectification; secondly inversely calculating coordinates ofpixels corresponding to pixels on the original image pixel by pixel by utilizing an inverse method; and finally performing pixel-by-pixel statistics and judgment whether pixel points are overstretched pixel points or not, forming a binary marker image of the overstretched region, and performing vectorization to obtain a vector file of the overstretched region, thereby achieving the purpose of automatically detecting the overstretched region in the optical remote sensing satellite orthoimage. The method has the remarkable effects that automatic detection of the overstretched region in the optical remote sensing satellite orthoimage is realized; the problems of time and labor waste and low efficiency of a conventional mode for manual visual identification of the overstretched region are solved; and the quality check efficiency of the optical remote sensing satellite orthoimage is greatly improved.