The invention discloses a 360-degree panoramic image unfolding method based on polar coordinates, and relates to the technical field of panoramic display. The width w and the height h of an unfolded panoramic image are obtained according to the inner circle radius r1 and the outer circle radius r2; stepping deltatheta and deltarho of the polar angle theta and the polar radius rho of the polar coordinates in a circular fish eye image are calculated, wherein the stepping deltatheta of the polar angle is obtained in a way that the arc 2pi of the whole circle is divided by the width w of the unfolded panoramic image; reverse coordinate mapping is adopted for avoiding generation of blank pixels after coordinate mapping, and the corresponding polar coordinates of the coordinates (i, j) after unfolding of the image in the circular fish eye image are (rho, theta); and the polar coordinates are converted into the pixel coordinates (x, y) in the circular fish eye image so as to obtain the unfolded panoramic image, wherein (x0, y0) are the central coordinates of the circular fish eye image. The method is more concise in calculation process and less in repeated calculation.