The invention relates to a structure light vision detection technology, in particular to a rapid extracting method for structure light welding seam image characteristic points. In the invention, an on-site programmable gate array and a soft-core processing system are used together for improving processing speed and reducing power consumption; and the rapid extracting task for structure light welding seam image characteristic points is divided by software and hardware to extract characteristic points by software and hardware cooperation. The invention comprises the following steps: building a Programmable System-on-Chip (PSoC); carrying out mathematical morphology processing and image preprocessing on structure light stripe-containing image which is acquired by a camera sensor by the on-site programmable gate array, wherein the mathematical morphology processing comprises filtering, image enhancement, dilation and erosion, and the image preprocessing comprises edge extraction and centre line extraction; and extracting characteristic points by the soft-core processing system. In the invention, production-line working way is used among steps, thereby improving image processing speed and meeting real-time requirement of seam tracking. The invention can be widely used in the field of laser automatic welding.