The invention discloses an air gap iron core used for a haulage motor transformer. The air gap iron core comprises an iron core column and an upper iron yoke which is located above the iron core column, and an air gap is arranged between the iron core column and the upper iron yoke; the air gap iron core further comprises clamping pieces which are located at the two sides of the upper iron yoke and are fixed in position, a check block which is used for tightly fitting the end part of the upper iron yoke is arranged between the two clamping pieces, and the check block is provided with a lower margin which is used for aligning and fitting the end face of the iron core column; the air gap iron core further comprises a tightly fixing component which is used for fixing the position of the check block relative to the clamping pieces, the iron core column and the upper iron yoke. The invention further discloses the haulage motor transformer which comprises the air gap iron core. According to the air gap iron core, the situation that locating moving occurs on the upper iron yoke and the iron core column is avoided, the air gap iron core is beneficial to the prevention of the situation that dislocation occurs on the upper iron yoke and the iron core column, and thus normal operating of the haulage motor transformer can be ensured.