In order to improve the efficiency of traffic incident detection algorithm in urban expressway and reduce the impact of incidents,basing on proposing the definition of lengthways time series of traffic parameters and defining abnormal traffic statuses clearly,the relation between abnormal traffic statuses and traffic incident is analyzed,the traffic status variability index is constructed using gain amplification principle,then automated detection algorithms for the traffic incident is designed.This method can not only detect the location of traffic incident but also the incidence of traffic incident,the result show that detection effect and robustness of this algorithms is better than classical algorithms.