The invention discloses a rapid reduction method for data streams in grid fault diagnosis, belongs to the technical field of processing of grid fault diagnosis data streams and has the advantages thatthe data stream reduction degree is high, data at a fault point after data stream reduction is not lost easily, and a failure node is located easily. The method comprises the following steps: high-current self-assessment failure rate and low-current self-assessment failure rate of each node are obtained, and high-current effective failure rate is stored into a high-current effective failure datatable; low-current effective failure rate is stored into a low-current effective failure data table; the current high-current data table and the current low-current data table are formed; a low-current difference data table is formed; father node mean and a father node variance of a child node are calculated, or a child node mean and a child node variance of a father node are calculated; the current node compression value table is obtained; a node attributive feature table is formed; node data is reduced; the failure node is located.