The present application provides an alarm method and device. The method includes: in response to a received alarm request, acquiring target data from a target database according to the alarm request, and determining a target processing condition and target alarm conditions according to the alarm request, where the target database includes vehicle data and road section data of at least one transportation subsystem; performing analysis and processing on the target data according to the target processing condition to obtain traffic flow information corresponding to a target road section, where the target road section is at least one road section indicated by the road section data; in response to determining that the traffic flow information meets a set of target alarm conditions, giving an alarm.