The DC motor, transmission mechnism, safety unit and electric control unit installed in a hand-cranked orchard simple type earth auger formed the electric power assistance system of orchard simple type earth auger The system’s performance showed: when the orchard simple type earth auger carried no load, when it was equipped with a drill bit with a diameter of 30 and 20 cm, the linearity coefficients between its average speed of rising and falling and the battery power consumption were 0.790, 0.910, 0.927 and 0.865, respectively, the linearity is high; when the orchard simple type earth auger was digging the earth after it was equipped with the same above mentioned drill bit, the electric power assistance system could raise the earth auger at speed of 1.32 or 1.43 cm/s, and there was no significant difference between the starting electrical current for the drill bit when it was digging and the starting electrical current for the drill bit when it was operating without digging.