The invention discloses a multi-split air conditioning system. The multi-split air conditioning system comprises one or more outdoor units and multiple indoor units. The multi-split air conditioning system is characterized in that each indoor unit comprises multiple indoor heat exchangers and multiple solenoid valves, wherein the indoor heat exchangers are in parallel connection, and the multiplesolenoid valves are connected with inlets and outlets of the corresponding indoor heat exchangers; and the multi-split air conditioning system further comprises a controller, the controller is used for controlling the multiple solenoid valves to be switched on and switched off and controlling the corresponding indoor heat exchangers to stop heat exchange operation when the multiple solenoid valvesare switched off, so that the load of the multi-split air conditioning system is lowered. The invention further discloses a control method and device of the multi-split air conditioning system and acomputer readable memory medium. By means of the multi-split air conditioning system, the control method and device thereof and the readable memory medium, operation reliability of the multi-split airconditioning system is improved.