Taking the centering of theodolite as study object, the images of station point are processed by the technology of digital image processing after being collected by CCD sensor. The centering deviation is a driving signal for high precision motorized positioning systems to achieve the automatic centering of theodolite. The original optics centering is transformed. The method of digital image processing is studied including image preprocessing and circle target center location algorithm. Hybrid filter and subpixel edge detection is adopted on this paper. The simulation result shows that the theodolite centering measurement method based on digital image processing can make up for the shortage of more repeat procedures. The measuring time is also shortened greatly, and the precision of the measuring method reaches the error scope value of 5.5μm as expected.