Abstract: A control device for soft starting and protecting overload of a motor in a power tool is disclosed. The control device comprises a power switch, a varistor, several diodes, several resistors, several capacitors, a relay, a transistor, a triac, and a microcontroller. The microcontroller is embedded with program such that, after the power switch is turned on, the microcontroller generates a smooth soft start voltage to drive the power tool. With the characteristics of power-control device, the voltage sent to motor is increased from low to full range. When the speed of motor is increased from low to the maximum, the microcontroller turns off the power-control device and turns on a relay.