A machine vision detection method includes receiving a three-dimensional image from a line laser, converting the three-dimensional image into a two-dimensional grayscale image, obtaining a boundary of a first component and a boundary of a second component in the two-dimensional grayscale image, determining N perpendicular lines between the boundary of the first component and the boundary of the second component, and calculating an average length of the N perpendicular lines as a gap between the first component and the second component. The three-dimensional image includes at least a portion of the boundary of the first component, at least a portion of the boundary of the second component, and a welding spot located on the boundary of the first or second component. N is a positive integer.