This paper presents an approach for remote screen synchronization by applying the association of spatio-temporal redundancy reductions (ASTR). The temporal redundancy between the current changed screen area and the previous frame is taken into account. By applying an improved SSC-APDS (Subsampling Search Candidates in Adjustable Partial Distortion Search) algorithm, the speed of the block motion estimation is increased obviously. Experimental results approve that this approach can save more bandwidth in transferring the screen data and reduce the overhead of the client. It has been used in a practical wireless application for conference projecting and cooperating named FreeSpeech with good performance.