In this paper, we propose a novel spatial join-based algorithm for Continuous Border Monitoring Query (CBMQ) processing, which we refer to as SJCBMQ. SJCBMQ transforms the CBMQ processing problems into the spatial join processing problems. Based on the transformation, SJCBMQ finds stream-query pairs which satisfy intersecting relationship. Another attractive contribution of our work is utilizing the locality characteristic of data streams. To take advantage of this characteristic, we cache the search result via an elaborate design. When a hit occurs, we reuse the cache result, avoiding re-evaluate the queries once again. Experimental results show that SJCBMQ significantly outperforms existing approaches in terms of both storage cost and search time.