Abstract: A method for Measuring displacement and attitude of smod on the blur in defocused images was studied in this paper. The tracking algorithm for image markers was also presenred. Four particular markers were set on the moving objects. The displacements of four markers were calculated respectively by the blur of their defocused images. The displacement of moving objects along optical axis was the average of four displacements of markers,and the attitude angle was calculated by the displacements of two diagonal markers. The experimental results show that the presented method was simple,less calculation,and could satisfy the requirements for measurement in real time. Its errors were also acceptable.