The utility model relates to a public road bridge drawing arrow point device for roof beam. This public road bridge drawing arrow point device for roof beam, including a level setting two crossbeams and the base that perpendicular roof beam was formed by connecting, bottom four corners at the base respectively is equipped with a wheel, the handrail of a vertical setting is equipped with on the top right side of base, the electrical cylinder that the level that is equipped with on the left base of handrail set up, electrical cylinder's telescopic link and the slide bar that sets up between two crossbeams link firmly, the slide bar slides in the card locates the recess of seting up along crossbeam length direction through the slider respectively at both ends about, it is provided with five nozzles to follow slide bar length direction interval on the slide bar, every nozzle all is linked together through transfer line that is equipped with the electrical ball valve and the bottom that sets up the liquid storage pot on the handrail. This public road bridge drawing arrow point device for roof beam, it is rational in infrastructure, convenient and practical, easy operation, labour saving and time saving utilizes the switch and the electrical cylinder's of nozzle cooperation, can once only accomplish the drawing of craspedodrome arrow point.