| Crack detection and measurement are accomplished by manual detection with crack scales, which is time-consuming and money-consuming. The research was proposed to detect and measure the cracks on the surface of concrete structure, based on computer vision technology. The measurement device was consumer-grade camera, which was relatively inexpensive. Crack detection involves image blurring, image enhancement, morphological operation, image distortion calibration, connected-domain labelling, isolated point elimination, and crack segmentation matching. Furthermore, the research calculated the length and width, as well as records and development direction of extracted crack pixels. Moreover, in the monotonic loading test of reinforced concrete beams, after taking photos of cracks on the beams and compared with the results by traditional methods, the proposed method attained the decent precision of the computer-vision based crack detection and measurement.