The utility model relates to a flat-bottomed aluminum alloy open-top car which comprises a chassis, end walls, side walls and a connecting rod, wherein the end walls are vertically arranged at the front and tail ends of the chassis, and the side walls are vertically arranged on both sides of the chassis; the chassis is connected with the side walls and the end walls by riveting or bolted connection so as to form a box structure; the connecting rod is arranged obliquely, a lower mounting seat at one end of the connecting rod is in bolted connection with the chassis, and an upper mounting seat at the other end of the connecting rod is connected with the side walls by riveting. Therefore, the flat-bottomed aluminum alloy open-top car disclosed by the utility model has the advantages that 1. the design is reasonable, and the structure is simple and completely practical; 2. the chassis of a car body is of a flat-bottomed structure, so that manufacturing and assembling operations are simple; and brake parts are arranged below the chassis, so that the maintenance space is large, and the maintenance efficiency is high; 3. compared with the all-steel structured car body, the open-top car is small in dead weight and large in loading; 4. the chassis is provided with an empty car lifting hole, and upper mounting seat of the connecting rod is also provided with an empty car lifting hole, so that empty cars can be lifted by using different forms of hooks.