The invention discloses a detection method of an abnormal event of multi-variable water quality parameter time sequence data. The detection method comprises the following steps: firstly, inputting a plurality of water quality parameter models; training and constructing a data driven predication model (BP model); analyzing multi-variable water quality time sequence data in a water supply pipe net and estimating the model; secondly, predicating through the BP model to obtain a predicated value of water quality data; comparing an actually measured value of a current state and the predicated value obtained by the predication model and carrying out error estimation and classification analysis, so as to determine a single-variable parameter abnormal event; classifying based on an error counting result, and updating and determining the event probability of single-variable water quality parameters through sequential Bayesian updating; carrying out multi-variable fusion decision-making and fusing information from a plurality of water quality monitoring indexes; providing a unified decision-making result and determining whether the water supply pipe net has the abnormal event on a specific node or not.