The invention provides a detecting method for an infrared image of a frozen river. The detecting method comprises the following steps: receiving an original infrared image to be processed by using a detecting device; generating a radiant energy feature map based on significance by using the detecting device according to the original infrared image; carrying out wavelet decomposition and Shearlet decomposition on the radiant energy feature map by using the detecting device through sub-band filtering to obtain a filtering result of the radiant energy feature map on a wavelet basis and a Shearlet basis; constructing an optimal model based on the wavelet basis and the Shearlet basis by using the detecting device; solving the optimal model by using the detecting device, and separating image components; and taking separated linear regions as final frozen river detecting results by using the detecting device. The detecting result is accurate.