The invention discloses a printed circuit board assembly and detection system which is used for detecting whether part assembly on a printed circuit board assembly structure has faults; the system includes a first light source, an image extraction device, a control device and a detection and analysis device. The first light source is used for projecting light to the back of the printed circuit board assembly structure, wherein the printed circuit board assembly structure is provided with a plurality of through holes for assembling a plurality of parts, and at least three fixing holes for fixing. The image extracting device is used for extracting a first front image of the printed circuit board assembly structure. The control device is used for controlling the first light source and the image extracting device, to make the image extracting device obtain the first front image after the first light source is started. The detection and analysis device is used for analyzing the first front image. If a through hole light spot is detected to appear, the printed circuit board assembly structure is judged to have a missing part.