hazards accordingly in step d if the value of th1 is greater than x the motor 82 is powered off and if the value of th1 is not greater than x it returns to step c the numerical value of x may be set according to design requirements for example a value of x which is 100 indicates that the electric motor is powered off after the overcurrent of the electric motor is exceeded 100 times the counters are employed so as to prevent the electric motor 82 from being undesirably powered off and affecting the normal work of the electric tool in which the current fluctuation of a typical electric motor exceeds a preset value occasionally by means of the control method when different working parts 8 are connected to the main body 6 the microcontroller 51 can select circuit parameters and current protection points suitable for the connected type of working part to ensure that the electric motor is at a normal state for the corresponding working part such that the working part can operate more safely and efficiently in addition to the judgment by sampling the current value of the electric motor 82 it is also possible to judge that the electric motor 82 is at a normal working state or an abnormal working state via other working parameter values of the electric motor for example a voltage or speed when the electric motor operates according to the disclosed combination electric tool of the present invention the control circuit and the microcontroller are provided on the main.