The invention discloses a mahjong machine and a slope tile discarding device thereof. Four integrated supports are connected end to end to form the square slope tile discarding device, and each integrated support is provided with a tile feeding part and a tile lifting part; each tile feeding part comprises a U-shaped tile storage groove which is integrally formed with the corresponding integrated support, wherein the tile storage groove is provided with a tile feeding guide rail, a tile feeding push head and a tile feeding drive mechanism; each tile feeding drive mechanism comprises a tile feeding motor, a drive winding wheel and a steel wire rope, multiple rolling needle grooves are formed in the tile feeding guide rails, rolling needles are embedded into the rolling needle grooves, the portions, in the tile storage grooves, of the steel wire ropes make rolling contact with the rolling needles, and gaps are maintained between the portions, in the tile storage grooves, of the steel wire ropes and the side walls of the tile feeding guide rails and/or the tile storage grooves. According to the mahjong machine and the slope tile discarding device thereof, the tile feeding support, provided with the large-arc-shaped tile storage part, of one party and the tile lifting part of the other adjacent party are both installed on the same integrated support, the four integrated supports are connected end to end to form the square slope tile discarding device, assembly is convenient, and the production efficiency is improved; sliding friction of the steel wire ropes is replaced by rolling friction, and therefore the service life and operation stability of the machine are improved.