The invention relates to a water tank for a high pressure resistance air pressure type flushing device. The water tank is formed by merging a plurality of cylindrical tanks which are arranged in parallel to each other, wherein inner cavities of the cylindrical tanks are cylinder cavities, and the circles at the cross sections of the cylindrical cavities are staggered, so that all the cylindrical cavities are communicated with each other; circular arcs are used for transition in staggered positions; upper end faces and lower end faces of the cylindrical tanks are semi-spherical surfaces; the bottoms of the cylindrical cavities are provided with flushing valve mounting holes; the tops of the cylindrical cavities are provided with flushing switch mounting holes; and the flushing valve mounting holes and the flushing switch mounting holes form flushing valve mounting cavities simultaneously. Because the water tank is formed by merging the plurality of the cylindrical tanks which are arranged in parallel to each other and has a reasonable structure that the circular arcs are adopted for transition in the staggered positions, the stress of a water tank body is reduced to the maximum degree; the mechanical strength is improved; difficult leakage of the water tank for the high pressure resistance air pressure type flushing device is simultaneously guaranteed; and the water tank can achieve the aim of high pressure resistance with small material consumption and reduce the cost.