An electrical tool, comprising: an AC power module connectable to an AC power source; a brushless motor drivably connected to an output shaft for applying a rotational force, the brushless motor comprising a rotor and a stator; a rectifier module for receiving an alternating current from the AC power module and converting the alternating current into direct current; a drive circuit configured to be connected to the brushless motor for driving the brushless motor; a controller connected to the drive circuit for outputting a control signal to the drive circuit to cause the drive circuit to drive the brushless motor; a capacitor connected between the rectifier module and the driving circuit; wherein a ratio of the capacitance value of the capacitor to a rated power of the brushless motor ranges from 20 μF/kW to 80 μF/kW, characterized by comprising: an EMI module connected between the AC power module and the rectifier module; a circuit board, with the capacitor, the rectifier module, and the EMI module arranged on the circuit board; wherein a ratio of the projected area of the capacitor on a maximum plane of the circuit board to a total area of the maximum plane of the circuit board is in the range of 1/50 to 1/15; and the EMI module includes a first capacitor, a second capacitor and a third capacitor, one end of the first capacitor connected with one voltage terminal of the AC power module, and the other end of the first capacitor connected with one end of the second capacitor, the other end of the second capacitor connected with another voltage terminal of the AC power module, one end of the third capacitor connected with a stator housing of the brushless motor and with the connection of the first capacitor and the second capacitor, and the other end of the third capacitor grounded. an AC power module connectable to an AC power source; a brushless motor drivably connected to an output shaft for applying a rotational force, the brushless motor comprising a rotor and a stator; a rectifier module for receiving an alternating current from the AC power module and converting the alternating current into direct current; a drive circuit configured to be connected to the brushless motor for driving the brushless motor; a controller connected to the drive circuit for outputting a control signal to the drive circuit to cause the drive circuit to drive the brushless motor; a capacitor connected between the rectifier module and the driving circuit; wherein a ratio of the capacitance value of the capacitor to a rated power of the brushless motor ranges from 20 μF/kW to 80 μF/kW, characterized by comprising: an EMI module connected between the AC power module and the rectifier module; a circuit board, with the capacitor, the rectifier module, and the EMI module arranged on the circuit board; wherein a ratio of the projected area of the capacitor on a maximum plane of the circuit board to a total area of the maximum plane of the circuit board is in the range of 1/50 to 1/15; and the EMI module includes a first capacitor, a second capacitor and a third capacitor, one end of the first capacitor connected with one voltage terminal of the AC power module, and the other end of the first capacitor connected with one end of the second capacitor, the other end of the second capacitor connected with another voltage terminal of the AC power module, one end of the third capacitor connected with a stator housing of the brushless motor and with the connection of the first capacitor and the second capacitor, and the other end of the third capacitor grounded. an EMI module connected between the AC power module and the rectifier module; a circuit board, with the capacitor, the rectifier module, and the EMI module arranged on the circuit board; wherein a ratio of the projected area of the capacitor on a maximum plane of the circuit board to a total area of the maximum plane of the circuit board is in the range of 1/50 to 1/15; and the EMI module includes a first capacitor, a second capacitor and a third capacitor, one end of the first capacitor connected with one voltage terminal of the AC power module, and the other end of the first capacitor connected with one end of the second capacitor, the other end of the second capacitor connected with another voltage terminal of the AC power module, one end of the third capacitor connected with a stator housing of the brushless motor and with the connection of the first capacitor and the second capacitor, and the other end of the third capacitor grounded.