A power device for an electric tool and system is provided that can power tool bodies of different electric tools. The power device includes a power control unit that receives a control instruction transmitted by the tool control unit and controls the motor according to control instructions. The power device not only improves the utilization rate of general modules, such as a motor and a battery pack, but also improves the expandability of the system, reduces the amount of programs in the power device, and eliminates the need to update the programs in the power device to be adapted to a new working body.