Structured spot extraction is an important basis for line structured light three-dimensional vision measurement.To overcome the difficulty of extracting structured spot in complex background light environment,a method of extracting structured spot based on time-domain differential imaging is proposed in this paper.In this paper,the circuit control line structure light and the imaging unit are synchronized,so that one frame of the two consecutive images contains structured spot and the other frame does not contain structured spot.By identifying the similarity characteristic parameters of the gray values of the two frames,extracting the potential area of the spot,and combining with the correlation region filtering,the structured spot can be effectively extracted.This method can accurately extract the low signal-to-noise ratio structured spot in complex background environment,and has high practical value for the related applications of structured spot such as line structure light three-dimensional vision measurement.