Abstract: In distributed data streams, the correlation analysis between data streams can be used to detect inner-relation of monitored objects. The paper presented an algorithm based on basic windows to measure correlations coefficient over distributed data streams. Formula for computing correlation coefficient was changed into so form which consisted of some factors that could be aggregated conveniently by method based on basic windows. Then factors among formula were counted respectively. In approach based on basic window, the data items among window were partitioned into a serial of basic windows, which were aggregated each. After window had been slidden random, previous partial results could be used to compute current window. Compared with aggregation on whole data items within window, the simulative experiment shows that the presented method can reduce the computing time of correlation coefficient on data streams.