The invention discloses a safety pre-warning system and a method for railway track construction. A real time GPS coordinate, a running speed, and a running direction of a train are acquired and uploaded to a server through installation of vehicle-mounted terminal equipment on the train; and a hand-held terminal worn by a site constructor acquires information of the train in ten kilometers running towards the direction of the constructor from the server according to the current GPS coordinate, the time that the train comes to the position of the constructor is judged according to the speed of the train and the distance between the train and the constructor and a voice prompt to the constructor is conducted, a discontinuous prompt to the constructor is conducted as time goes by, and an advanced avoid is achieved. Compared with a traditional forewarning mode, a station protector is not needed to be arranged, human cost is reduced, and the advantage is more obvious particularly on the condition of a long construction interval.