The invention discloses a building construction separation line reminding device. The building construction separation line reminding device comprises a first protection rod, bases and a bearing. Separation belts are connected to the left side of the first protection rod. The bases are fixed to the tail ends of the first protection rod and a second protection rod. Fixing blocks are symmetrically disposed on the right side of the first protection rod. Elastic rods are symmetrically disposed on the left side of the second protection rod. A belt winding rod is installed in the second protection rod, the bearing is in installed at the tail end of the belt winding rod, a connecting rod is fixed to the top end of the interior of the second protection rod, and a hand rocker is installed on the rear part of the second protection rod. Water pumps are installed in the bases, and circular holes are formed in the fixing blocks. By arranging fluorescent strips on the separation belts at equal intervals, the building construction separation line reminding device can conveniently remind people that the area is a construction dangerous area at night, thereby avoiding the phenomenon that people enter by mistake, and the occurrence of safety hazards is avoided.