Abstract: Visual locating technology is one of main development direction of mobile robot locating. Aiming at problem of poor real-time performance of traditional visual positioning technology, this paper proposes a fast visual locating technology based on adaptive down sampling. Down sampling rate is calculated firstly based on previous size characteristic and minimum resolution size. Secondly down sampling and image segmentation are made on next image. Object locating zone in original source image are determined according to coordinates of object and down sampling rate. Then image segmentation and feature extraction of source image of the area are made. Size of feature extraction is taken as an image input, and required features extraction of visual location are taken as robot locating solution. Thus visual positioning time is effectively reduced with ensured visual positioning accuracy. Experiments show that it takes 20.23 s for traditional technology to process 100 figures while it takes 1.78 s for technology given out by this paper, which is only 8.8% of traditional technology. This technology can reduce image processing time effectively and improve real-time performance of mobile robot locating.