The invention discloses an infrared imaging-based on-line dynamic automatic laying defect detection apparatus and an infrared imaging-based on-line dynamic automatic laying defect detection method. The infrared imaging-based on-line dynamic automatic laying defect detection apparatus comprises a laying unit and a defect detection unit, the laying unit comprises a spool, feed rollers, a laying press roller, a hot blast tube, and a laying die, the defect detection unit comprises an infrared heat source, an infrared thermal imager, and an image processing system, a prepreg tape is arranged on the spool, the prepreg tape is sequentially transmissively connected to the feed rollers, the laying press roller and the laying die, the infrared heat source is arranged over the laying die, the infrared thermal imager is arranged over the laying die, and the infrared thermal imager is connected to the image processing system. The invention can implement the rapid and accurate detection of laying defects, has high capability in identifying typical laying defects, and can implement the quantitative analysis of defect dimensions.