The invention relates to an early warning method for car safe backing of a tracked battery car in tunnel construction. An air cylinder is installed at the tail of a shield tunneling machine trailer and is connected with a bumper bar which is connected with a signal emitter, and the signal emitter and a camera are installed at the tail of a battery car haulage motor; a control cabinet, a loudspeaker and an image displayer are installed in a driving cab of the battery car, and a control button of the air cylinder is installed on the control cabinet; when the battery car is backed and is close to the tail of the shield tunneling machine trailer by 50 m, the bumper bar is in a horizontal anti-bumping state, the signal emitter emits an electromagnetic wave early warning signal to a signal receiver which transmits the early warning signal into a central processing unit of the control cabinet through a data cable, through switching, the central processing unit transmits the signal to the loudspeaker, the loudspeaker emits voice broadcast, and deceleration is conducted; and when the tail of the battery car haulage motor gradually gets close to the bumper bar, through the image displayer, a driver starts to back the battery car and brake to enable the battery car to enter the shield tunneling machine trailer at slow speed, and car safe backing early warning of the tracked battery car in a tunnel is achieved accordingly.