A radiant tube type spherical high-speed mixed bed inlet water distribution device with two stages of perforated plates is composed of a radiant tube type water distributor, a first-stage perforated plate water distributor and a second-stage perforated plate water distributor. Wherein the radiant tube type water distributor consists of a water distribution disc and an eight-claw type water distribution device, and aims to uniformly guide water flow entering the high-speed mixed bed to the whole cross section of the mixed bed from a central area; the first-stage perforated plate water distributor is composed of two layers of perforated plates with coincident upper and lower openings and a base plate, is connected with the radiant tube type water distributor, and aims to guide impact water flow on the section surface of the high-speed mixed bed downwards through uniformly distributed small holes, so that the flow velocity of the impact water flow after passing through the small holes isreduced; the second-stage perforated plate water distributor is composed of a layer of perforated plate and supporting strips, the perforated plate and the supporting strips are distributed on the whole section, water flow is further evenly distributed, on one hand, downward water flow is distributed again and cannot flow down from the side edge, and on the other hand, the impact distance of the downward water flow is smaller than the height of a water cushion layer in the high-speed mixed bed.