This paper presents an efficient joint disparity-motion estimation algorithm for stereo sequence CODEC. The disparity vectors are estimated by using the left and right motion vectors and the previous disparity vectors in each time frame. In order to obtain more accurate disparity vectors, we include spatial prediction process after joint estimation. From joint estimation and spatial prediction, we can obtain accurate disparity vectors and then increase coding efficiency. Finally, we proposed the backward quadtree decomposition, which helps the encoder to have more detailed disparity vector map without transmitting additional coding bits for quadtree information. We confirmed the superior performance of the proposed method from simulation results.