The utility model relates to a closure building on an open and deep soft foundation river. A bottom protection concrete plate is built on a river bed, and comb piers are built on the bottom protection concrete plate. Comb piers are connected by steel wires, and the comb piers and the steel wires form a stone block fence. The closure building on the open and deep soft foundation river has the benefits as follows: the bottom protection concert plate is built on the river bed, as a result, scouring damage to a river bed soft foundation, caused by high-speed water flow at a closure gap is reduced; the comb piers built on the bottom protection concrete plate reduces the material diameter and loss of special material used in river closure construction, lowers toss intensity and difficulty of closure construction, and meanwhile, utilizes comb overflow fluid state to quickly form backwater in front of a gate, so that a good flow dividing condition is created. If necessary, a comb protection bottom can be effectively combined with a cofferdam anti-seepage system, accordingly, the construction cost is saved, the construction period is shortened, and the problems of high fall, high difficulty in large flow rate deep soft foundation river bed closure construction, long construction time and high construction cost are effectively solved.