Abstract: The new image segmentation algorithm based on generalized harmonic mean distance is proposed.The Otsu’s thresholding method is a kind of representative image thresholding segmentation algorithm，and it has widely applied in image segmentation field by reason of its many characteristics such as computing simplicity，fast speed and performance stability.The traditional Otsu’s thresholding method is a kind of minimum variation thresholding algorithm based on Euclidean distance and is devoid of robust performance in image segmentation because of Euclidean distance without adjustable parameter.This paper first replaces the Euclidean distance in Otsu’s thresholding segmentation method with the generalized harmonic mean distance and obtains a kind of new robust image segmentation algorithm，then the method of choosing its optimal parameter in new segmentation algorithm is brought forward.A large quantity of experimental results show that the new segmentation algorithm is more effective than otsu’s method.