The utility model discloses a range finding pursuit early warning device and train for train, it includes directional aerial, a transceiver circuits, the 2nd transceiver circuits and treater, and a transceiver circuits, the 2nd transceiver circuits all are connected with the directional aerial electricity, and a transceiver circuits, the 2nd transceiver circuits all are connected with the treater electricity, a transceiver circuits is used for after receiving the the first signal that the treater sent, adopts directional aerial to receive and carries specific pseudorandom code's distance signal and carry out the transfer with distance signal and send, the 2nd transceiver circuits is used for after receiving the second signal that the treater sent, adopts the directional aerial initiative to send the distance signal who carries specific pseudorandom code and receive the distance signal who transmits through the transfer and send distance signal for the treater, the treater is used for receiving distance signal and generates range signal output. The utility model discloses need not other positioning device accuracies and acquire and supervise front and back train set car distance, prevent the rear -end collision, improved driving safety.