The invention discloses a bridge crack detection method. Due to the fact that manual marking has certain subjectivity, the pavement crack detection precision depends on experience knowledge of experts, and experience lacks objectivity in quantitative analysis. The method comprises the following steps: 1, collecting images of a detected bridge floor one by one to obtain a bridge floor image set; 2,splicing images; 3, detecting crack; 4, extracting crack parameter. According to the invention, the image acquisition and processing technology replaces human eyes to complete automatic nondestructive detection of the bridge crack, and has very important practical significance for research of the bridge crack detection technology in a complex terrain environment. On one hand, the construction safety is enhanced, and on the other hand, the operation maneuverability and flexibility are improved. According to the invention, fidelity splicing of multiple groups of bridge deck images is realized,the image splicing precision and efficiency are improved, a working foundation is laid for subsequent bridge crack image detection, and a technical reference is provided for image splicing detection in other fields.