The utility model belongs to the technical field of the underwater pipeline construction and specifically relates to a floating platform is assembled under water to siphon piping, this floating platform of its characterized in that bottom is adopted and is sealed the rectangle box, sets up corresponding semicircular notch in box both sides top, sets up sealed rubber ring along the semicircular notch edge, the box top sets up the water inlet, box inner bottom position is put and still is provided with immersible pump and water -resistant power, and immersible pump water outlet pipeline followsthe box top and stretches out the box. Simple structure is reliable for this floating platform, convenient to use, and it is blank to have remedied landlocked lake siphon piping equipment.