The present invention provides There is provided a unitary air conditioning system with temperature and humidity loosely-coupled control and a use method. The system includes a fresh air inlet, a return air inlet, an air mixing mechanism, a front-end air guide mechanism, a first and a second heat exchangers, a back-end air guide mechanism, an air supply outlet, and an air exhaust outlet. The fresh air inlet and the return air inlet are in communication with the air mixing mechanism, which is in communication with one end of an air flow passage of each of the first and the second heat exchangers through the front-end air guide mechanism; and the other ends of the air flow passages of the first and the second heat exchangers are respectively in communication with the air supply outlet and the air exhaust outlet through the back-end air guide mechanism.