Traditional length-measurement methods cannot detect pitch. Accordingly, in this work, an optical cable pitch detection method based on machine vision is proposed. This method uses a laser velocimeter for detecting the speed of a production line and generates corresponding pulses to trigger the acquisition information by an industrial camera. A detection system was built by combining low angle with backlight illumination. Furthermore, a preprocessing operation was used to solve the instability of overlapping geometric properties of gray levels. To improve the positioning accuracy, an automatic template construction method is proposed to effectively construct matching templates. A template partition precise-positioning method was used to solve the problem of direct matching misjudgment; then the commutation point was matched and identified and the pitch length was detected. Theoretical analysis and experimental verification reveal that the error between the measured and standard pitch results is within 0.02-0.10 mm, which meets engineering requirements, and the system runs steadily and reliably. The proposed method provides a new way to detect optical cable pitch.