The invention relates to a fully-automatic mahjong machine comprising a board sending system, a board loading system, a board lifting system and a large shuffling disc. The board sending system comprises four board sending mechanisms, each board sending mechanism comprises a transmission rack, and a board sending motor, a board absorbing wheel, a transmission belt, a transmission platform, a board inlet guiding piece and a board outlet guiding piece fixed on the transmission rack; a board sending channel is arranged at the upper end of the transmission platform, the board absorbing wheel is tightly attached at the lower end of a board inlet opening of the board sending channel, the board inlet guiding piece is positioned above the board absorbing wheel, the board outlet guiding piece is positioned at a board outlet opening of the board inlet channel, the board sending motor is used for driving a motor guiding wheel, the motor guiding wheel is positioned below the transmission platform, and the transmission belt loops the motor guiding wheel, the board absorbing wheel and the transmission platform. In the invention, for the mahjong boards with different widths, the board sending mechanism of the mahjong machine can run normally by only replacing the corresponding board inlet guiding piece and the board outlet guiding piece, and a transmission rack cover does not need to be changed, so that the operation is simple and convenient, and the board inlet guiding piece and the board outlet guiding piece has extremely low production cost relative to the transmission rack cover.