The invention discloses an impact mechanism in an electric impact drill. The impact mechanism comprises a fixed impact block arranged on the outer side of a spindle in a clearance sleeving manner. The part, in front of the fixed impact block, of the spindle is fixedly sleeved with a movable impact block. Fluctuation tooth patterns are arranged on the two opposite end faces of the fixed impact block and the movable impact block. The outer side of the part, in front of the movable impact block, of the spindle is further sleeved with an impact guiding block in a clearance manner. The outer side of the part, in front of the impact guiding block, of the spindle is sleeved with an impact adjusting block in a clearance manner. At least one limiting notch is formed in the front end face of the impact guiding block. Limiting bosses corresponding to the limiting notches in a one-to-one manner are arranged on the rear end face of the impact adjusting block. The outer side of the part, between the impact adjusting block and a gear case, of the spindle is sleeved with a return spring in a clearance manner. A shell is further provided with a torsion cup capable of being arranged on the outer side of the front end of the gear case in a sleeving manner. The impact adjusting block is arranged in the torsion cup, and the torsion cup can drive the impact adjusting block to rotate. The above impact mechanism is simpler in structure, and accordingly the gear shifting operation of the impact adjusting block is more convenient.