A lifting cabinet includes a transmission assembly and a power unit for raising and lowering a shelf. The transmission assembly comprises a first transmission unit, comprising a screw rod which is connected with a driving device and a sliding piece which is connected with the lifting shelf, and the sliding piece is coupled to the screw rod. The screw rod rotates under the action of the driving device and drives the sliding piece to move back and forth along the axis of the screw rod; and then the sliding piece drives the lifting shelf to move up and down. For the lifting cabinet and the power unit thereof, the transmission assembly converts a rotary motion outputted from the driving device into a linear motion through the cooperation between the screw rod and the sliding piece, and a greater axial force is thereby outputted. Thus, a relatively small motor with a lower output torque can be used in the lifting cabinet to drive a lifting shelf of the same weight when compared to the conventional lifting cabinet, and the problem of large motor in conventional lifting cabinet taking up too much space is thereby solved.