Abstract: For the requirements of biomimetic robotfish in object recognition and tracking, using the image segmentation algorithm based on threshold and an edge detection algorithm based on Sobel operator,an image segmentation algorithm based on adaptive threshold-adjustment strategy of target images is presented.The proposed algorithm can solve the problem that the image segmentation algorithm based on fixed threshold cannot adapt to the light variation.The proposed algorithm is applied to the underwater object recognition task of biomimetic robotfish and its validity is tested through experiments.