A novel method combining BEMD and receiver operating characteristics (ROC) curve is presented in this paper to solve the problem that the threshold is greatly affected by personal experience when underwater image edge detection is performed using a bi-dimensional empirical mode decomposition (BEMD) algorithm. Firstly, the BEMD algorithm is employed to decompose an underwater image into several intrinsic mode functions (IMFs) and a residual. Then several IMF images are computed using combinations of the Canny detector parameters, and the image binaryzation results are generated accordingly. The ideal BEMD edge feature extraction maps are estimated using correspondence threshold which is optimized by ROC analysis. The experimental results show that the proposed algorithm is able to avoid the operation error caused by manual setting of the detection threshold, and to adaptively set the image feature detection threshold. The proposed method has been proved to be accuracy and effectiveness by the underwater image processing examples.