The invention relates to a seat for a tractor cab. A left supporting assembly and a right supporting assembly are oppositely arranged, and a vertically-arranged seat back is arranged on one sides of the left supporting assembly and the right supporting assembly. A seat base is arranged on the upper portions of the left supporting assembly and the right supporting assembly, and one end of the seatbase is rotatably connected with the seat back. A magnet strip is arranged on one side of the upper end of the seat back, and an electromagnet strip corresponding to the magnet strip is arranged on the seat back. The left supporting assembly comprises two first supporting blocks and a connecting block located between the two first supporting blocks. The right supporting assembly comprises a secondsupporting block, a rotating block, a bearing block and a lifting air cylinder; the rotatable rotating block is arranged at the upper end of the second supporting block; the lower portion of the other end of the rotating block is connected with the lifting air cylinder through the bearing block; and the lifting air cylinder is arranged in a containing hole in a bottom plate of the cab. A gearboxin the seat does not need to bear the weight of a driver, thus people can conveniently repair and maintain the gearbox, the life of the gearbox is long, and the cab can further be cooled through an electric fan.