A pressure tank type plate floor of a ship is formed in a way that a steel plate is compressed into a cross section shape with interphased Z shapes or reverse Z shapes. The pressure tank type plate floor of the ship has good strength and stiffness in the out-of-plane direction. Therefore the thickness of the pressure tank type plate floor is reduced by about 50% compared with the traditional plate floor under the condition that the strength and stiffness in the vertical direction are kept the same with the traditional plate floor, and stiffener materials and the fabrication and installation labor-hour can be reduced; therefore the pressure tank type plate floor has multiple advantages that the cost is low, the efficiency is high, the dead load of the ship is reduced, the effective loading capacity of the ship is improved, and the like. The pressure tank type plate floor has two forms according to the different positions of the pressure tank type plate floor relative to a longitudinal member of the ship, an A-type pressure tank plate floor is formed in way that a Z-shaped web of the pressure tank plate floor is aligned at a longitudinal bone of the ship, and a transition bracket in the traditional form needs to be added; a B-type pressure tank plate floor is formed in way that the longitudinal bone of the ship penetrates through the middle of a tank, the transition bracket in the traditional form does not need to be added, while a novel and integral-form partner plate needs to be added.