The invention belongs to the technical field of road traffic detection, and particularly discloses a method for detecting the abnormal condition of urban road traffic by utilizing the GPS (Global Positioning System) data of public buses. The method comprises the following steps: firstly, carrying out preprocessing on the GPS data of the public buses, extracting and calculating effective parameters so as to realize representation for traffic conditions; secondly, traffic history condition analysis: specifically including the steps of traffic condition feature extraction, traffic condition mode identification, quantification definition of traffic abnormal condition and the like; thirdly, traffic abnormal condition detection: specifically including the two steps of traffic condition real-time variation trend analysis and traffic abnormal condition distinguishing. The method for detecting the abnormal condition of urban road traffic provided by the invention gives full play to the advantages of mass GPS data of the public buses, the conditions of urban road traffic can be accurately represented, the normal condition and abnormal condition of urban traffic can be clearly distinguished, and analysis on the historical situation and real-time variation trend of urban road traffic condition can be realized at the same time.