Aiming at the low detection rate of black polar ship targets（BPST）in visible remote sensing images（VRSI） taken by remote sensing satellites and high-altitude UAV at sea，a ship target detection method based on dark primary color prior and constant false-alarm rate principle is proposed in this paper. In this method，the target image is preprocessed to obtain its dark channel image（DCI）. The DCI is used as the input of 2-D-CFAR detection method，and the local statistical gray mean and variance are used as target detection characteristics. The suspected targets’locations are completed by selecting appropriate target determination threshold and target spatial distribution information. Finally，the suspected targets’ sets are verified by using the established ship target feature vector to remove false alarms and output the final target detection results. Experimental results show that this method has a more accurate detection effect on ship targets in VRSI，with a total detection rate of 96.07%. It also acts as a“magnifying glass”for BPST which are difficult to be distinguished by human visual，with a detection rate of 86.71%. It greatly improves the detection rate of BPST in VRSI，which has certain guiding significance to optimize the innovation of black polar target detection method，and also provides a new idea for the application of dark channel prior principle.