The invention discloses a positive pressure type wall mounting fresh air system. The system comprises a box body and a control circuit board, wherein filters are arranged on one sides of ventilation grids on the inner walls of the left side and the right side of the box body and on one side, far away from the ventilation grids, of an air inlet, and a heat exchanger is fixedly arranged between theair inlet of the inner wall of the box body and an air outlet; an air outlet high-efficiency fan and an air inlet high-efficiency fan are fixedly arranged on the inner wall of the box body, a swing head motor is fixedly arranged between the air inlet high-efficiency fan and the air outlet high-efficiency fan, and a control circuit board is fixedly arranged on one side of the air inlet high-efficiency fan of the inner wall of the box body. According to the system, a grid door is automatically opened through a swing head motor, the high-efficiency fan is started, a one-way valve installed on theair inlet and outlet is utilized, so that the purification internal circulation mode is realized, and the purification capability is ensured under the simultaneous filtration action of the multiple filters; and a full-heat-exchange technology is enabled the fresh air system to have two-way flow synchronous air replacement purification capability, and further have internal circulation re-purification capability, and the use effect is good.