The invention particularly discloses an environment video monitoring and early warning system based on a computer network. The road condition video information is acquired by a road camera in a videoacquisition module; the video is sent to a virtual map module by a server; the virtual map module is used for integrating video information of all cameras; a map analysis module analyzes the congestion position and the congestion time and feeds the congestion position and the congestion time back to the server; the server sends the congestion position and the congestion time to a red light controlmodule and a road control module; therefore, the traffic lights can be adjusted according to the crowded degree when the traffic lights are on crowded places. A sign for warning front road congestionis also arranged around the crowded road section; meanwhile, a road condition prediction module can predict roads which may be crowded according to a large amount of previous data and send the data to the server, the data are displayed on the road sign, and the client can display real-time road crowding conditions and can also know the predicted crowded roads in advance.