The embodiment of the invention provides a method and a device for detecting a network. The method comprises the steps of acquiring analyzed data of one or more target network performance indexes, wherein the analysis data of each target network performance index comprises measured values corresponding to the target network performance indexes at multiple collection time points; analyzing the analysis data to acquire a plurality of data sequences, wherein each data sequence comprises the plurality of measured values corresponding to one target network performance index at the multiple collection time points, and the plurality of measured values are arranged in a chronological order; determining an abnormal collection time point or an abnormal data sequence according to the plurality of data sequences; and determining the network performance index corresponding to the abnormal collection time point or the abnormal data sequence to be an abnormal network performance index. According to the method and the device provided by the embodiment of the invention, the abnormal network performance index can be effectively recognized through analyzing the plurality of data sequences of one or more target network performance indexes.