Abstract: An air-conditioning system is constructed to include a full-heat heat exchanger, the full-heat heat exchanger having a first inlet and a second inlet arranged at right angles, a first air filter unit connected to the first inlet of the full-heat heat exchanger and adapted to filter air passing through the first inlet of the full-heat heat exchanger, the first air filter unit being formed of a primary coarse particle wire gauze filter, a HEPA (high efficiency particulate air filter) core, an active carbon coated wire gauze filter, and an optical catalytic wheel, and first fan means disposed in front of the full-heat heat exchanger and adapted to draw outside air into the first air filter unit.