The invention discloses an alarm associated variable detection method and system based on relevance, wherein the method comprises the steps of establishing a binary time sequence through an associated variable; and quickly and automatically acquiring an abnormal data section from historical data accurately by combining a time sequence sectioning method and a correlation coefficient trend method so as to detect abnormal data, thereby providing favorable conditions for a dynamic alarm threshold value design of a multi-variable alarm system, so that disturbance alarm is reduced, the efficiency of treating alarm by a field operator is improved, and the production safety is guaranteed.