The invention discloses a tunnel entrance section vehicle flow control method comprising the following steps: S1, vehicles running in a tunnel are enabled to run in different lanes according to vehicle size, and a vehicle flow at an entrance of a tunnel is subjected to different lane running control; S2, illumination difference between a lane part positioned inside a tunnel entrance and a lane part positioned outside the tunnel entrance, average vehicle flow speed difference between the lane part positioned inside the tunnel entrance and the lane part positioned outside the tunnel entrance, and a inside-the-tunnel vehicle flow of each lane are obtained; S3, based on the illumination difference between the lane part positioned inside the tunnel entrance and the lane part positioned outside the tunnel entrance, average vehicle flow speed difference between the lane part positioned inside the tunnel entrance and the lane part positioned outside the tunnel entrance, and a inside-the-tunnel vehicle flow of each lane, a BP neutral network classification and identification algorithm is used for obtaining an optimal speed limit value and reasonable acousto-optic early warning prompt information of each lane; S4, variable speed limit prompt information is respectively displayed on corresponding lanes, and acousto-optic early warning prompts about vehicle speed of the vehicles in the tunnel are given. Via the tunnel entrance section vehicle flow control method, overall control over speed of vehicle flows on large and small lanes can be realized, individual vehicles which touch a height limit bar are subjected to violation detection and punishment, a current situation that traffic accidents frequently occur at an entrance section of a driveway tunnel can be improved, and traffic efficiency and a safety level of the driveway tunnel can be raised.